Power Hydraulics
Michael J. Pinches, John G. Ashby
Automation Advisory Service,
Faculty of Technology,
Sheffield City Polytechnic, UKCONTENTS
PREFACE
1 INTRODUCTION I
LI Hydraulic piinciple$ I
LU Properties of fiutcL I
1.1.2 Units I
1.13 Pressure of 4 liquid I
1.1.4 Flow of a fluid 5
1.1,5 Work dene 8
1,2 Hydraulic symbols 9
2 PUMPS 15
2.1 Types of pump ] 5
2.1.1 Rotary pumps 18
2-1.2 Reciprocating pumps 22
2J.3 Variable-displacement pump-control systems 2S
2.L4 Pump selection 3d
2.2 Pumping circuits 34
2.2.1 Single fixed-displacement pump 35
2.2.2 Single fixed-displacement pump with accumulator JO
2.2.3 Multi-pump 38
2.2,4 Variable-delivery pump 4 1
2.3 Pump drives 4 1
2.4 Pump circuit design study 43
3 HYDRAULIC VALVES .57
3.1 Pressure-comtoI valves
3.LI Relief valves -s
3.1.2 Counterbalance valves W
3.1.3 Pressure sequence valves g
3J.4 Pressure-redurmg valvvs
3,2 Flow-comrd valves
J.2.1 Speed control of a cylinder
J.2.2 Threc-pori nr bypass-type llow’cuntrol valve
3.2.3 Priority flow control
3.2.4 Bridge networks
J.2.5 Multi-speed systems using fiow-control valves RS
3.2.6 FIom dividersnii
»3 Diirdioiial coniiol saho 93
A VI l heck salves 9«
3.3.2 PopiWl valves ,
AM Slidhlg spdW-IM* diii’Ct
A .1.4 Iwo Mage diuvihMMl conwl valve* no
a i s Vake M/e* and lumicndalinc 112
A.4 Cartridge sakes HA
A.4.1 Poppet type cartridge sakes 121
A. 4 .2 Spy’ll – 1v |te cm11idpc s aIse* 123
A 5 Mobile hydraulic takes 124
A.5.1 Yakc arrangements
4_ A CTI 1 I.- 141 kJ flkbSm \ . 127
4 1 Hydraulic cs tinders
4.1,1 Displacemeni cylinders
4.1,2 Single-acting cylinders IJi
4.1.3 Double-acting cylinders 1 ‘3
4.1.4 Acceleration and deceleration of cylinder loads 140
4.1,5 Cylinder mountings and strength calculations
4.2 Semi-rotary actuators
4.2-1 Vane-type actuators 152
4.2.2 Piston-type actuators 152
4.2.3 Helical screw actuator 154
4.2.4 Control of semi-rotary actuators 155
43 Hydraulic motors 155
4.3.1 Generated form types 135
4.3.2 Piston-type motors 159
4,4 Hydraulic motor circuits 163
4.4.1 Open circuit transmissions 163
4.4.2 Closed-loop transmissions 168
4.4.3 Multi-motor circuits 1711
4,5 Motor circuit design examples 172
5 FLUIDS FOR HYDRAULIC SYSTEMS 180
5,1 Hydraulic fluids
5.1,1 An outline of the developmem of hydraulic fluids IHU
180
5-1 2 Properties ot hydraulic fluids
ISO
185
18″
189
5.13 Hydraulic fluids survey
5.1.4 Future developments
5.2 Fluid contamination control
5-2.1 Energy contamination
5.2,2 Gaseous contamination 189
5.2.3 Liquid contamination I^i
5.2 4 Microbiological contamination 192
5.2.5 Paniculate contamination (dirt) 194
«ml filtration t«htlo|ogl
5.3 1 Filter construction
194
200
53 2 Fihration technology 200
533 Filter location 202
5.3.4 Filter sizing 20′
212Contents ix
5.4 Leakage eonhoi 214
5.4.1 ilvdrnulii; conduits 214
5-4 2 High pressure tube cmmix nous 217
5 4.3 Hydiaulic how. 225
5.4.4 SuppniK and clamps. 230
5.4.5 Circml accessories 230
5.4.6 Pipewoik elimination and shui’blicaiii’iik 212
5.4.” Seal protecturn 233
5.4.S Rules 1’or leakage control 234
inDRAUl IC SYSTEM DESIGN 235
6.1 Design criteria 235
6.1.1 Design informalion required 236
6.2 Summary of basic formulae and rules 237
6.2.1 Fluid How 237
6.2.2 Pressure losses 240
6.2.3 Cylinder formulae 241
6.2.4 Pump formulae 242
6.2.5 Hydraulic motor formulae 244
6,3 Power -pack design 245
63,1 Layout 245
63.2 Reservoirs 24?
633 Centralized hydraulic systems 253
6.4 Hydraulic accumulators 254
6,4.1 Types of accumulators 254
6.4.2 Accumulator applications 259
6.43 Operation and safety precautions 265
6,5 Hydraulic intensifiers 267
6.6 Design study—a simple hydraulic press 268
6.7 Design study—conveyor feed system 287
HYDRAULIC SYSTEM MAINTENANCE 296
7.1 Equipment and practices which benehi maintenance 296
7.1.1 flood housekeeping practice 296
7.1.2 Fluid storage and handling 300
7.13 Installations and commissioning of hydraulic systems 301
7,1.4 Routine maintenance 303
7,2 Trouble shooting in hydraulic systems 304
7.2.] Test equipment 304
7.2.2 General rules for hydraulic maintenance engineers 305
7.23 The concept of logical fault finding 305
73 Solutions to fault-finding exercises 323
CONTROL SYSTEMS 328
8.i Servo control 329
8.2 Valve servo systems 330
8.2, 1 Valve lap 330
8.23 Mechanical feedback 331
8.23 Sysiem response 333CoH/enfs
s 2,4 Elcctro-bydrantic .servo valves 338
8.2,5 System t espouse mid stability 340
8,3 Pump servo systems 340
8.3,1 Effect of leakage 341
8-3,2 Effect of compressibility 342
8.3.3 Natural frequency 344
8.3.4 Hydraulic stiffness 344
8.3.5 Damping ratio 345
8-4 Proportional valves 350
8.4.1 Force control 350
8.4.2 Force position control 351
8,4.3 Spool positional control 352
8.4.4 Proportional pressure control 354
8,4.5 Two-stage proportional valves 356
8.4.6 Proportional flow control 358
8.4.7 Electrical control of proportional valves 360
8.5 Proportional versus servo valves 360
8.5,1 Response speed and dynamic characteristics 360
8.5 2 Hysteresis effect 361
8.5.3 Null position 361
8.6 Some applications of proportional control valves 362
8.6.1 Control of actuators 362
8.6.2 Pump control systems 363
APPENDIX EXERCISES AND SOLUTIONS 367
A J Circuitry questions 367
A.2 Hydraulic calculations 376
A.3 Design problems 3S3
A.4 Solutions to Section A.2 388
FURTHER READING 391
INDEX 393FURTHER READING
Hitler; rd hydraulics
Pugh, H. (1980) TAe Hydraulic Age. Mechanical Engineering Publications. London
Fluid mechanics
John, J, E. and Haberman, W. L. (1980) to Fluid Mechanics, Prentice Hall.
Englewood Cliff’s, NJ,
Roberson. J. A, and Crowe, C. T. (I9?5) Fluid Mechanics, Houghion Mifflin, New
York.
Reference books
Warring, R. H., ed. (1983) The Hydraulic Handbook, 8th edn, Trade & Technical Press, Morden,
Surrey.
Hydraulic Technical Data, Trade & Technical Press, Morden, Surrey
Pumps
Lambeck, R. P. (1983) Hydraulic Pumps and Motors, Marcel Dekker. New York.
Fluids
Tourrei, R. and Wright. E. P. (1979) Per/owmnte Testing of Hydraulic Fluids. Heyden/lnslttuteof
Petroleum, Loudon.
Cunlrul and servo
Guilion. M. (1969) Hydrutdif Serio Systems. Buiterworth, London.
Harrison, H. L. and Hollinger. J. G. (1969) /lu/omufic Controls, International Textbook Co..
London.
McCloy; D. and Marlin, H. R. (1980) Control Of Fluid Power. Ellis Horwood. New York.
Ptppingtr, J. D. (1984) Hydraulic Falces and Control. Marcel Dekker, New York.
R«d, E. W. and Larman, J. S. (1985) Fitud Power wtth Microprocessor Control: wfroJHt/io/i,
Greinke Hall, Hcmel Hempstead
Stringer, j, D. (1976) Hydraulic System Analysts, Macmillan, London.INDEX
P.sl-j number’, in bold type indicate the main subject reference.
absolute rating, 203. 207, 211, 250, 296
absorption, 193
accumulator. 36, 48 54. 234, 254, 272 6,
293, 302
applications 259 67, 272
back-up bottles, 258. 275
bag. 258
charging. 265-7
circuit. 36. 40, 53. 64. 100, 276. 277, 305
dead load, 254—5
free surface. 256
gas loaded, 255-9
isolating valve. 53
piston, 257, 265
precharge. 49, 259. 273, 293. 303
pressure testing, 266
safety, 265-7, 305
safety circuit. 100, 267
sizing, 260, 273
spring loaded, 25 5
actuators, 127
design information 236
additives, 180, 184. 192
adiabatic expansion and compression of a gas.
- 257, 259, 260, 275. 294
adsorption, 194
aeration. 95, 190, 251
aeration control, 191, 251
air blast cooler, 252
air bleed valve, 42, 297
air breather, 199, 211, 250 1, 296. 301
tur bubbles, 183, 190
air motor, 42
a>r saturation. )9|
analog. 328
anti.burst valve, 231
^li-cavjtaiion check valve, 126, 163, 169
^nb-foaming additives, 192
a»li-]ungc device. 74. 76
an< -oxidant, J 80 ^li-syphon holes, 191, 251 an’i-vibration mounts, 245, 301 anu wear agents, 185 armature, 99, 105. 106, 351, 361 axial piston pump, 22, 25 axial piston motor, 160 ANSI (American National Standards Institute), 110 bacteriological growth, 194 baffles, 252 balanced vane pump, 21 ball motor, 160 basic formulae (summary), 237 bell housing, 246 bellows, 146 bent axis motor, 160, 162 bent axis pump, 23, 25, 31 beta raring. 203, 204. 211 bite ring, 218. 220 bladder, 192, 258 9 bleed-off filler, 208 blecd’off flow control, 77 block diagrams, 310. 314, 329, 341, 347, 359, 360 bonded washer, 223 boost pump, 169, 179. 319 brake valve. 66. 168, 169, 322 Bramah, Joseph, 268 bridge network. 86, 210 British Standard (US), 139. 181. 214, 220, 288, 297 British Standard Pipe Thread (BSP), 220, 222 bubble point test, 203 buckling length, 147-8, 289 buckling loud. 148, 150, 288 bulk modulus, 18. 183, 262-3, 342-4 bypass tiller, 208 bypass flow control, 83, 176 bypass valve, 204, 206. 213. 269, 303 cam rotor motor, 159 cartridge valve. 99. Ill, 233 (see ufao Valve, cartridge) cavitation, 163, 189, 191, 251, 299 centralized hydraulic systems, 253, 288Index 394 certrifugal pump. CUTOP. IIO, 195, 221. 399 check valve (sec 3 ahe. check) soft seal. 93 chlorinated hydrocarbons, I SI choke pack. 108. 292, 516 circuit breaker, 68 clamps, lube and hose. 250 clean up loop. 207, 210. 211. 5 11, 314 clean hydraulic oil, 19$. 19* cleanliness standards, 195 cleanliness target levels. 212 clearance in components. 198 closed loop control, 329, 360 closed loop transmission. 35. 168-171, 178 commissioning, 301, 302. 365 component malfunction, 309 compressibility, 183. 342 compression fining, 218, 2)9 condition monitoring, 297 constani How control, 29, 175 constant power control, 28. 17$, 179, 286 contamination analysis. 298, 299 contaminant coding, 196, 197 contamination control, 189 control systems, 328 conversion coupling, 219 conveyor feed system, 28* copying device. 332, 336 corrosion inhibitor, 180, 185 counterbalancing. 64, 264 counterbalance valve, 64-6, 76. 95, 297. 309. 315 coupling shaft, 246. 303 tube, 217-25 cracking pressure, 93 crescent seal, 19 cross-line relief. 61. 167, 292, 322 custom built power packs, 245 cylinder, 127 acceleration and deceleration, 140 5 displacement, 127, 128, 132. 138 double acting, 127. 133 51, 153 dynamic thrust , 136. 241 cushioning, 142 5, 155 cushion pressures, M2 formulae, 128, 134, 136 8, 140, 241 maximum speed, 145 mournings. 146 operating temperatures. 145 piston rod buckling strength. M8 piston rod ends. 146 piston rod protective covers, 146 regenerative, 137-9, 149 seal friction, 136 speed control, 75 single acting. 133. 126. 127, 254, 269, 273 standard metric, 139, 142, 151, 285. 288 sialic thrust. 136, 241 strength. H7 50 stop tube, 148 synchronization, 89 telescopic, 130- 2 through rod, 139 wear, 299, 309 damping orifice, 30, 75 damping ratio, 344 5 dead zone, 331. 352 deceleration valve, 72 decompression, 95-7, 184 Delrin, 93 design criteria, 235 information. 236 study, 268 detem, 105 diaphragm (jee Flexible separator) diatomaceous earth, 201 diffuser, 192. 251, 292 digital, 328, ,150, 365 DIN standards, 110, 111, 113. 215. 218, 219, 223 directional control valves, 93 (see also Valve, directional control) dirt in systems effect, 199 origin, 194, 198, 206 dirt fust, 209, 240 size categories, 199 tolerance, 20 displacement cylinder, 127-32, 138 dissolved air, 190 dither control, 338, 359, 360 double acting cylinder, 127, 133 -51 dual relief valve, 61 efficiencies pump and motor, 16, |7, 156, 166 7, 173 9, 243-4. 2912, 346 system. 43 56,271 87 elastomer seals, 101, 128, MS, 187, 259 electrohydraulic servo valve, 338 40 electrostatic contamination, 190 electrostatic filtration, 202 energy contamination, 189 Engler, 181 entrained air, 183, 190, 252 equations of motion, 140 Euler’s strut theory, 14830$ failure tawstropbie. 198. 2(H) dcjradJUioii, 198, 200 fault ^06 finding chart, 312* 315 feedback. 329 33. 338* 353, 361 filler vapacity, 202. 213. 240 constr uet iou. 206 comamination time curves* 206 cold start conditions. 205, 213, 296 ckxiroMatk’, 202 element beta rating. 203 bubble point resi* 203 changing, 211. 303 collapse pressure, 204 condition indicator, 205, 302, 314 depth type, 201* 202 tlo« capacity, 213 media. 201 rating 203, 207. 211, 212, 250, 296 spin-on, 211. 294 surface type. 201. 202 housing, 200 location, 47, 207-12 magnetic, 202 pressure drop through, 213 suing. 212-3. 240 lire resistant fluid. 180, 186-7. 194, 190 Miration technology, 200 first order system, 334 flange connection, 221 flared fittings. 217-9, 223 flapper type servo valve, 339, 361 flexible separator, 192, 199, 250-1, 258-9 float switch, 251, 256 flow control bleed off, 77 bypass, 83 5 meter in 75 B8, J68, 293 meter out. 76-88, 168, 284 vahes, 70 (jfe also Valve, flow control) flow divider, 89-92 flow meter , 304 flow through an orifice, 70 2, 332 Au* velocity, 6. 216 fluid flow. 5, JOS, 237 fluids (see Hydraulic fluid) nuihing* 302 flushing valve, 170 Naming, |8J. ] H4 form tool, 1 12 ^equency response, 336 gas laws, 49, 257, 275 gaseous coiittiimnution, PX) gear moior. 156, 157 gem pump, 19, 31. 45 generated lolnr (geruliir), 20, 155, 157 heal dissipation, 190, 24g heat energy, 190 high Mater-base Hinds (HWBI’1, 186, 188, 189 hi-lo, 39. 63, 271 hose break valve, 231 hydraulic conduits, 214 (see utw Hydraulic tube dwef hydraulic- hose) hydraulic fluids, eno hydraulic fluid additives, 180. 184, 185. 192 characteristics, 188 classification, 180 I compatibility, 188 conditioners, 252 contamination, 189, 298, 304, 305. 309 contamination control, 189-213, 296 future development, 187 handling, 300 mineral oil, 181. 185, 288 oil in water emulsions (HWBF)* 186, 188, 189* 252 operating temperature, 249. 252 phosphate ester, 181, 187, 190 sampling, 195, 297, 302 selection, 187 storage, 300 water glycol, 181. 186. 187 water-in-oil (invert) emulsion* 186-8 water removal, 193 hydraulic hose, 215-9 burst pressure. 226 end fittings, 227, 229 failure, 228 installation, 228, 3OL selection, 228 suction, 229, 301 supports, 229, 230* 301 types. 225 working pressure, 226 hydraulic motor circuits. 163 hydraulic molars, 155 (see u/so Motors) hydraulic power, 8, 9. 17 hvdrauhe press. 24, 39. 63, 65, 91 3, 95-7, 149 design study, 268 hydraulic stillness, 344 hydraulic symbols, 9, 58, 63, 69. 84, 86, 87, 89, 94. 109 hydraulic tube, 114 coned fittings. 220 connections, 217 25 lutings, 217-25396 flanges. 220 flow rating^ 216 installation. 224,. 301 pickling, 225 staple connector, 222 weld fittings, 220 working pressures, 215 hydrocapsuk. 176 hydrostatic braking, !Ci9 hydrostatic transmissions, 62, 103, 163 characteristics, ]65, !7l closed loop, 168 70. 177, 209, .119, 341 constant power, 165 circuit, 163 8. 175 hysteresis effect, 36 1 inhibitors, 185 installation, 224, 301 integrated circuit, 1I2t 123 intensifiesLion, 90, 93. 267 intensifier, 267, 280 interfaces. 11 1 ISO {International Standards Organisation), 1 10, 181. 195, 196 international reference numbers, 110, 195 inlravanc, 2 1 invert emulsion, 186-8 isentropic expansion and compression, 50, 257 isothermal expansion and compression, 49, 257, 275, 2M jet pipe servo, 1 , 339 JIC (Joint Industrial Council), 217, 222, 245 kickdown sequence valve, 68 kinematic viscosity, IBI free p/yo Viscosity) KR tube coupling, 219 laminar tlow, 6, 215, 239 land (spool}, 104, 330 Jap, 330, 331 l.aplacc, 333 8, 342 4. 349 50 Last Chance litter. 209 leakage coefficient, 341 4, 146 50 compensation, 263 conirol. 214. 234 internaI, I56, 159, J6S. 179, 297. 3Mb J4| level switch, 251, 256 linear actuators, 127 transducer, 352 liquid coniaminalion, 192 lock valw, 87 H logic element, J J2 23 (see alm Valve, cartridge) logic valve pilot control sources, 1 19 poppet type, 113-21 Judex remote switching, I 18 spoof type, 123 3 switching of multiple elements, H9 kgleaf fauh finding, 305, 3OH, 315 27 I orxlon Hydraulic ^bwer Co.. 25.1 lubrication. 101, 184-8 magnetic filter, 202 magnetic separator. 202 magnetism, 190 magnitude ratio, 337 maintenance, routine 299, 303 make-up pump. 163, 168, 320 manifold. 123, 232 4, 301 manual overrides, 107, 108 manual servo, 25-7. 179, 320, 322 mean filtration rating. 203 mechanical efficiency’ (fee Torque efficiency) mechanical feedback, 33J mechanical servo valve, 264, 331. 336 mcler in, 75-88, 168, 293 meter out, 76-88, 168, 284 microbiological contamination, 194 mineral oil, 181, 185, 288 mobile hydraulic valves, J23 arrangements, 124-6 modularized package, 113, 123 monoblock valve, 124 motion control vahc, 67, J 70 motor, 155 axial piston, 160 ball, 160 cam rotor, 159 characteristics, 162. 174 circuiu, 163, ?]7, 319 Circuit design examples, 172. 176 eltkkncies, 166 -7, L73-9. 244, 29 f, 346 formulae, 163-6, 244, 346 freewheel, 163, 168 gear, 156 gerotoi, 157 leakage. 156, 159. !?9 141 orbit. 157 radial piston, 5&i 3 sizing, 290 torque. 164, pg xane, ]58 variable displacement, 158-9, 161-6 motors in parallel, 172 motors in series, 17 1 multi-pass test. 204 nnilii-pump ^iicuiu, 38 41 46-8, 65. 27J, 3M, 292. 316 NFPA (National Fluid Power AssOciiM>un)-
110, 299
NPT (National Pipe Thread). 222. 223fruits
natural frequeiKv. 544
needle valve. ”I
neon indicatois. 10″
NC< reference number. LII
nominal rating, 203. 206
non-return valve (w Valve, check)
notched spool, 104, 116, 552
null point, 331 , ’61
diagram. 337. 338
‘O’ ring compression finings, 219
oil cooler, 190. 192, 240. 252
oil healer. 252
oil immersed solenoid, 106
oil-irwaier emulsion, 186, 188, 189, 252
oiI- 1iiuaict micro-emulsion, 189
open circuit (loop) transmission, 35, 163. 167
open Loop control, 329
operating temperature, 145, 249, 298. 306
orbit motor, 157
Orifice flow, 7D- 2. 332, 358
overall efficiency, 17, 166-7, 174-6. 179,
243-4, 292, 346
Ovcrccnter valve, 65-7. 168
overlap. 331
oxidation, 189
Oxidation inhibitor, 185
parallel connection. 124, 172
panicle
analysis, 197
counting, 195, 298
distribution, 196 7
sizes, 195. 198, 199
particulate contamination, 194 200. 206, 297,
304 (see oho Dirt)
Pascal’s laws, 4, 268
patch test. 298
phase angle, 337
phosphale ester, 181, 187. 190
pickling. 225, 301
pilot control sources, HW. 119. 271
pilot operated check valve. 94. 95, 99, 103,
112, 263, 264. 293, 309
Pilot pressure unloading, 62
piloi io dose check valve, 97
Pipe fitting, 217 25
pipe flow, 238
pipe supports, 229. 230. 30 1
piston rod buckling. 147 50
piston rod ends, 146
Pneumatics. I. 42, 253
Polytropic expansion and compression of a
gas, 257
Poppi-t valves, 59. 98-100, 112 121
Port identification, 11
port relief valve, 61
.397
pom point. 183, |R4
power pack, 245, 292, Wl. 311
Po/i1larc coupling. 219
prcfill valve, 95, 96, 281, 285
pressure compensation
pumps, 27, 54. 175, 272. 276. 284 6, 292
valves, 73. 74. «4, 121, 122. 304. 358. 359
pressure control cartridge valves, 120, 121
pressure control valves, 57 (see zr/jo Valve.
pressure control)
pressure drop, 103, 240
head, 5
intensification, 90. 93
line filter, 169, 208, 211, 296
losses, 240
of a liquid. I
operated directional control valve, 107
override, 59, 62
reducing valve, 69. 70. 123
surge (damping), 262
switch, 14, 36. 52, 149, 205, 276-9. 320
zone, 19
priority flow control, 85
properties of fluids, I
proportional amplifier. 360
proportional flow control. 358 60
pressure control, 354
pressure reducing valve, 354
pressure relief valve, 354
two stage valves, 356
versus servo valves, 340
proportional valves. 121. 123. 350
proportional valve
applications, 293, 362 6
characteristics, 351, 360
force control. 350
force, position control, 351
notched spool, 357
spool position, 353
pulsation damper, 225, 261
pump characteristics, 45, 175
delivery. 32
drives, 4!
drive speed, 32
cllkicucics, 16, 17, |76, 243 4, 292. 346
formulae, 15 7. 242 3, 342, 346
location. 245
noise, 33. 322
operating pt essme, 30 2
selection, 30, 17«, 291
servo system, 34(1
pump types, IS
axial piston, 22, 31, 320
centrifugal, 15
gear (external), 19. 31, 45.46
gear (gerotor), 20
gear (internal), 19, 31Index
noii-posiiisc displacement. 15
plunger, 24. Al
positive displacement, 15 35
radial piston, 24, 25
reciprocating, 22
rotaty, IS
tandem, 46
vane, 20, 21, 31
variable delivery. 21, 25 31. II, 175, 286.
292, 302, 345, 363
pumping circuits. 35, 363
push rod, 105
quick release coupling, 230, 231
Q-pump, 33
radial piston pump, 24, 25
radial piston motor. ItI-3
ramp down’, 359
ramp input, 334-6
ramp ’up’, 359
Redwood, 181
regeneration, 103
regenerative circuit, 137-9, 149
relative density, 180
relief valve, 27-9, 35, 39, 42, 58-64, 75-85.
91, 120-3. 168. 176, 270. 277. 284.
302, 309, 314, 320
ball, 59
cracking pressure, 59
cross line, 61, 167, 292, 322
differential poppet, 59. 60
direct acting, 59. 358
filter, 208
guided piston, 59
pilot operated, 59-61. 120, 122. 321
port relief, 61
remote operation, 61
selection, 62
solenoid controlled. 61, 121
unloader, 39, 62
remote switching of cartridge demcni, 1 18
reservoir
cooling effect, 248 50
design, 250 2
filling, 296 301
function, 247, 251
heater, 252
shape, 248
size, 33, 247, 249. 295
types, 247
restrictor cartridge. J 16
restrictor check, 97
return line filler, 176, 208. 211, 296, 314
reusable fillings, 227
reverse flow filter, 209
Reynolds number, 239
louny actuator Istr motor)
nisi inhibitor, 180, 185
sal ct v regulations, 266
sampling vahe, 297
sandwich plale (block), 61. 97, 233
Sayboli, INI
scavenging, 169, 170
seal friciion. 136
seal protection, 233
sealed reservoir, 192
semi-rotary actuator, 127, 152,236
chain and sprocket. 154
control, 155
helical screw, 155
lever arm, 154
rack and pinion, 153. 154
vane, 152, 154
sequence valve, 67 9, 282, 297
series connection, 125. 170
servo control, 25. 322, 329, 360 I, 365
servo system stability. 340
servo valve, 302, 339, 361
servo valve filter. 207, 209
sharp edged orifice, 73, 358
shear stability, 182
shut-off valve, 245. 299. 301, 315, 320
shuttle valve, 98, 169, 293
side cylinders, 282, 284
single acting cylinder, 127, 133
sinusoidal input, 336
SAE (Society of Automotive Engineers), 217,
221, 222, 227
soil scat valve, 93
soft -switching, 106, 113, 116
solenoid, 12, 106 ($ee uho Valve, directional
control)
controlled relief valve, 61
manual Override, 107
operation, 105, 351
operated cartridge valve, 117
pilot valve, 47, 53. 60, 99, 108
specific gravity, ISO
spool
notched, 104. 116. 352, 357
shapes, icm
spool valve
cartridge. Ill, 121-3
center condition, 102-4, 168
pressure drop, 103
stroke limiter, 109
iiunsitiou states, 101, 102
standby power supply, 253, 262
standard metric cylinders, 139, 140
standards organizations, 110, 180, 217
staple connector. 222
star-delta starter. 41
Lprr/C’
uaH-up “il”?.
skip ring. 1’1
stop nibes, 148
vainer, 192. 20?, 251. 315
streamline Hois, 6. 215
stroke limiter, nJ, 109
suction line filter, 2C\ 208, 211,. 296
suction /one. 19
swaged lining, 22
swash plate, 22, 25 31. 321
symbols, 9 14 (see Hydraulic symbols)
synchronizing valve, 89 90
synthetic fluid, 180, 18?
system damping, 340
efficiency, 27] -87
response, 333 8
start-up, 302. 305
stiffness. 191
tandem connection, 126
telescopic cylinder, 130-2
test equipment. 304
test points, 231, 233, 297, 299. 304, 314
thermal expansion, 184. 262
threaded connectors, 217-20. 222 4
three port flow control valve, 83. 85-6
through rod cylinder, 139
Lorque efficiency, 16, 17, 166 7, 243-4
transition state (valve spool). 100. 102
transmissions (sec Hydrostatic transmissions)
tree branching. 314
Triple-lok” rube fitting, 217
trouble shooting, 304, 310. 314
turbulent flow, 6, 239
two stage directional control valves, 108, 112,
270, 292. 316. 356
two stage pressure control valves, 59, 70, 120,- 321, 257
two stage sequence valve, 68. 122
underlap, 331, 361
units, 1 3, 237 8
unit step input, 331
unloader valve, 39, 62. 100
valve,
cartridge, 99, 112, 233
flow control, 122
logic element , J 12 23
normally dosed, 115
operation, 114
orifice, 177
P’lol control sources. 119
Puppet type. 113 -21
pressure control, 121
pressure reducing, 123
remote switching, 118
399
restrictor poppet, 116
spool type, 1 1 3, 121 3
spool valve equivalent. 120
switching, 1 18 20
check (non-rcturn), 10, 36, 39, 40, 65. 67,
71, 93. 99, 109. 112, 113, 123, 163.
-
- 299, 318. 322
bypass, 204. 206, 213
pilot operated, 94, 103. 1 12, 263. 264,
293, 309
pilot to close, 97
prefill, 95 7. 28K 285
restrictor, 97
sandwich, 61, 97. 233
shuttle, 98, 169, 293
direct acting, 101, 309
directional control. 93
identification of actuator position, 111
operators, 105
pilot operated, 107-9
poppet solenoid, 99, 112
sliding spool, 100, 112
solenoid operated, 36, 47, 101, 105, 106,
322
spool center conditions, 102-4, 168
spool stroke limiter, 109
spool transition states, 101, 102
three position, 88, 102
two stage, 108, 112, 270, 292, 316, 356
flow control 70 (see also Flow control), 209,
275, 309
bypass (three port), 83 -6
deceleration, 72
divider, 89, 90
needle, 7 1
pressure compensated, 73 6, 83, 122, 293
priority, 85, 86
viscosity compensated, 73
mobile, 123
monoblock, 124
paialk-l connection, 124
scries connection. 125
tandem connection, 126
valve actuation, 101, 105, Ml
valve constant, 71, 332
valve interfaces, 1 1 1
valve lap, 330, 361
valve pressure control, 12, 57, 120, 121, 354
counterbalaitec, 64 6. 76, 95, 297. 309, 315
uvercenter, 65 7, 168
pressure inducing, 69, 70, 123
iclief, 58 64 (see uh<> Relief valve)
sequence, 67 9, 282. 297
valve, servo systems, 330
valve slack, 61. 97, 232, 233
vane motor. 158, 159
vane pump. 20, 21,314 (Ml
vapor pressure, 186
vector diagram, 33 7
vehicle suspensions, 259, 264 5
velocity fuse. 231
velocity in pipes, 6, 7, 239
venting. 41, 61 4, 115
vent port, 60 4, 120
viscosity, 6. 73, 102, 152, 159, 181, 182,
185 9, 288
viscosity index, 181, 182. 184, 188
viscosity pressure characteristics, 182
viscosity temperature characteristics, 182
viscosity (temperature) compensation, 73. 358
volumetric efficiency, 16, 156, 166, 173-4,
- 299, 318. 322
- 321, 257
- 179, 243, 290 1
volumetric strain, 18. 183
volumetric stress, 18, 183
water-absorbing polymers. 193 4
water based fluids, IRO, 186, 194
water-in-oil (contamination), 193, 300
water-in-oil (invert) emulsion. 186, 187,
water glycol, 181. 186, 187
water hammer, 262
water removal, 193 4
wear, 298, 309
wet pin solenoid, 105. 106
wire mesh separator, 192, 252
work done, 4. 8. 164
welded connections, 220
welded nipple, 221
wiper ring, 130. 131, 13.3
zero lap. 33L 332, 361
CONTENTS
PREFACE
dn, PUMPS
xi
1 INTRODUCTION ]
1.1 Hydraulic principles 1
1.1.1 Properties of fluids ]
aleceOmits 1
1.1.3 Pressure of a liquid 1
1.1.4 Flow of a fluid 5
1.1.5 Work done 8
1.2 Hydraulic symbols 9
15
2.1 Types of pump IS
2.1.1 Rotary pumps \ 18
2.1.2 Reciprocating pumps WD)
2.1.3 Variable-displacement pump-control systems 25
2.1.4 Pump selection 30
2.2 Pumping circuits 34
2.2.1 Single fixed-displacement pump 35
2.2.2 Single fixed-displacement pump with accumulator 36
2.2.3 Multi-pump 38
2.2.4 Variable-delivery pump 4]
2.3 Pump drives 41
2.4 Pump circuit design study 43
3 HYDRAULIC VALVES a
Sa
3.1 Pressure-control valves yf 57
3.1.1 Relief valves Li 58
3.1.2 Counterbalance valves 64
3.1.3 Pressure sequence valves 67
3.1.4 Pressure-reducing valves 69
3.2 Flow-control valves 70
3.2.1 Speed control of a cylinder 75
3.2.2 Three-port or bypass-type flow-control valve 83
3.2.3 Priority flow control 85
3.2.4 Bridge networks 86
3.2.5 Multi-speed systems using flow-control valves 88
3.2.6 Flow dividers 89viii Contents
3.3 Directional control valves ve 93
3.3.1 Check valves 93
3.3.2 Poppet valves 98
3.3.3 Sliding spool-type directional control valves 100
3.3.4 Two-stage directional control valves 108
3.3.5 Valve sizes and nomenclature 110
3.4 Cartridge valves 112
3.4.1 Poppet-type cartridge valves L133
3.4.2 Spool-type cartridge valves 121
3.5 Mobile hydraulic valves 123
3.5.1 Valve arrangements 124
4 ACTUATORS [27
4.1 Hydraulic cylinders / 127
4.1.1 Displacement cylinders x 128
4.1.2 Single-acting cylinders 133
4.1.3 Double-acting cylinders 133
4.1.4 Acceleration and deceleration of cylinder loads 140
4.1.5 Cylinder mountings and strength calculations 146
4.2 Semi-rotary actuators 152
4.2.1 Vane-type actuators 2
4.2.2 Piston-type actuators 2
4.2.3 Helical screw actuator 154
4.2.4 Control of semi-rotary actuators P55
4.3 Hydraulic motors 155
4.3.1 Generated form types 155
4.3.2 Piston-type motors 159
4.4 Hydraulic motor circuits 163
4.4.1 Open circuit transmissions 163
4.4.2 Closed-loop transmissions 168
4.4.3 Multi-motor circuits 170
4.5 Motor circuit design examples 172
5 FLUIDS FOR HYDRAULIC SYSTEMS 180
5.1 Hydraulic fluids 180
5.1.1 An outline of the development of hydraulic fluids 4 180
5.1.2 Properties of hydraulic fluids 180
5.1.3 Hydraulic fluids survey 185
5.1.4 Future developments 187
5.2 Fluid contamination control 189
5.2.1 Energy contamination 189
5.2.2 Gaseous contamination 190
5.2.3 Liquid contamination 192
5.2.4 Microbiological contamination 194
5.2.5 Particulate contamination (dirt) 194
5.3 Filter construction and filtration technology 200
5.3.1 Filter construction 200
5.3.2 Filtration technology 202
5.3.3 Filter location 207
5.3.4 Filter sizing 212Contents
5.4 Leakage control
5.4.1 Hydraulic conduits
5.4.2 High-pressure tube connections
5.4.3 Hydraulic hoses
5.4.4 Supports and clamps
5.4.5 Circuit accessories
5.4.6 Pipework elimination and simplification
5.4.7 Seal protection
5.4.8 Rules for leakage control
6 HYDRAULIC SYSTEM DESIGN
6.1 Design criteria
6.1.1 Design information required
6.2 Summary of basic formulae and rules
6.2.1 Fluid flow
6.2.2 Pressure losses
6.2.3 Cylinder formulae
6.2.4 Pump formulae
6.2.5 Hydraulic motor formulae
6.3 Power-pack design
6.3.1 Layout
6.3.2 Reservoirs
6.3.3 Centralized hydraulic systems
6.4 Hydraulic accumulators
6.4.1 Types of accumulators
6.4.2 Accumulator applications
6.4.3 Operation and safety precautions
6.5 Hydraulic intensifiers
6.6 Design study—a simple hydraulic press
6.7 Design study—conveyor feed system
HYDRAULIC SYSTEM MAINTENANCE
7.1 Equipment and practices which benefit maintenance
7.1.1 Good housekeeping practice
7.1.2 Fluid storage and handling
7.1.3 Installations and commissioning of hydraulic systems
7.1.4 Routine maintenance
7.2 Trouble shooting in hydraulic systems
7.2.1 Test equipment
7.2.2 General rules for hydraulic maintenance engineers
7.2.3 The concept of logical fault finding
7.3 Solutions to fault-finding exercises
CONTROL SYSTEMS
8.1 Servo control
8.2 Valve servo systems
8.2.1 Valve lap
8.2.2 Mechanical feedback
8.2.3 System response8.2.4 Electro-hydraulic servo valves
8.2.5 System response and stability
8.3 Pump servo systems
8.3.1 Effect of leakage
8.3.2 Effect of compressibility
8.3.3 Natural frequency
8.3.4 Hydraulic stiffness
8.3.5 Damping ratio
8.4 Proportional valves
8.4.1 Force control
8.4.2 Force position control
8.4.3 Spool positional control
8.4.4 Proportional pressure control
8.4.5 Two-stage proportional valves
8.4.6 Proportional flow control
8.4.7 Electrical control of proportional valves
8.5 Proportional versus servo valves
8.5.1 Response speed and dynamic characteristics
8.5.2 Hysteresis effect
8.5.3 Null position
8.6 Some applications of proportional control valves
8.6.1 Control of actuators
8.6.2 Pump control systems
APPENDIX EXERCISES AND SOLUTIONS
A.1 Circuitry questions
A.2 Hydraulic calculations
A.3 Design problems
A.4 Solutions to Section A.2
FURTHER READING
INDEX
Contents
INDEX
Page numbers in bold type indicate the main subject reference.
absolute rating, 203, 207, 211, 250, 296
absorption, 193
accumulator, 36, 48—54, 234, 254, 272-6,
293, 302
applications 259—67, 272
back-up bottles, 258, 275
bag, 258
charging, 265—7
circuit, 36, 40, 53, 64, 100, 276, 277, 305
dead load, 254—5
free surface, 256
gas loaded, 255—9
isolating valve, 53
piston, 257, 265
precharge, 49, 259, 273, 293, 303
pressure testing, 266
safety, 265-7, 305
safety circuit, 100, 267
sizing, 260, 273
spring loaded, 255
actuators, 127
design information 236
additives, 180, 184, 192
adiabatic expansion and compression of a gas,
50, 257, 259, 260, 275, 294
adsorption, 194
aeration, 95, 190, 251
aeration control, 191, 251
air blast cooler, 252
air bleed valve, 42, 297
air breather, 199, 211, 250-1, 296, 301
air bubbles, 183, 190
air motor, 42
air saturation, 191
analog, 328
anti-burst valve, 231
anti-cavitation check valve, 126, 163, 169
anti-foaming additives, 192
anti-lunge device, 74, 76
anti-oxidant, 180
anti-syphon holes, 191, 251
anti-vibration mounts, 245, 301
anti-wear agents, 185
armature, 99, 105, 106, 351, 361
axial piston pump, 22, |25
axial piston motor, 160
ANSI (American National Standards
Institute), 110
bacteriological growth, 194
baffles, 252
balanced vane pump, 21
ball motor, 160
basic formulae (summary), 237
bell housing, 246
bellows, 146
bent axis motor, 160, 162
bent axis pump, 23, 25, 31
beta rating, 203, 204, 211
bite ring, 218, 220
bladder, 192, 258—9
bleed-off filter, 208
bleed-off flow control, 77
block diagrams, 310, 314, 329, 341, 347, 359,
360
bonded washer, 223
boost pump, 169, 179, 319
brake valve, 66, 168, 169, 322
Bramah, Joseph, 268
bridge network, 86, 210
British Standard (BS), 139, 181, 214, 220,
288, 297
British Standard Pipe Thread (BSP), 220, 222
bubble point test, 203
“buckling length, 147-8, 289
buckling load, 148, 150, 288
bulk modulus, 18, 183, 262—3, 342—4
bypass filter, 208
bypass flow control, 83, 176
bypass valve, 204, 206, 213, 269, 303
cam rotor motor, 159
cartridge valve, 99, 112, 233 (see also Valve,
cartridge)
cavitation, 163, 189, 191, 251, 299
centralized hydraulic systems, 253, 288394 Index
centrifugal pump, 15
CETOP, 110, 195, 221, 299
check valve (see Valve, check)
soft seat, 93
chlorinated hydrocarbons, 181
choke pack, 108, 292, 316
circuit breaker, 68
clamps, tube and hose, 230
clean up loop, 207, 210, 211, 311, 314
clean hydraulic oil, 195, 197
cleanliness standards, 195
cleanliness target levels, 212
clearances in components, 198
closed loop control, 329, 360
closed loop transmission, 35, 168-171, 178
commissioning, 301, 302, 365
component malfunction, 309
compressibility, 183, 342
compression fitting, 218, 219
condition monitoring, 297
constant flow control, 29, 175
constant power control, 28, 175, 179, 286
contamination analysis, 298, 299
contaminant coding, 196, 197
contamination control, 189
control systems, 328
conversion coupling, 219
conveyor feed system, 287
copying device, 332, 336
corrosion inhibitor, 180, 185
counterbalancing, 64, 264
counterbalance valve, 64—6, 76, 95, 297, 309,
315
coupling
shaft, 246, 303
tube, 217—25
cracking pressure, 93
crescent seal, 19
cross-line relief, 61, 167, 292, 322
custom built power packs, 245
cylinder, 127
acceleration and deceleration, 140—5
displacement, 127, 128, 132, 138
double acting, 127, 133-51, 153
dynamic thrust, 136, 241
cushioning, 142—5, 155
cushion pressures, 142
formulae, 128, 134, 136-8, 140, 241
maximum speed, 145
mountings, 146
operating temperatures, 145
piston rod buckling strength, 148
piston rod ends, 146
piston rod protective covers, 146
regenerative, 137—9, 149
seal friction, 136
speed control, 75
single acting, 133, 126, 127, 254, 269,
273
standard metric, 139, 142, 151, 285, 288
static thrust, 136, 241
strength, 147—5S0
stop tube, 148
synchronization, 89
telescopic, 130—2
through rod, 139
wear, 299, 309
damping orifice, 30, 75
damping ratio, 344—5
dead zone, 331, 352
deceleration valve, 72
decompression, 95—7, 184
Delrin, 93
design
criteria, 235
information, 236
study, 268
detent, 105
diaphragm (see Flexible separator)
diatomaceous earth, 201
diffuser, 192, 251, 292
digital, 328, 350, 365
DIN standards, 110, 111, 113, 215; 218, 219,
223
directional control valves, 93 (see also Valve,
directional control)
dirt in systems
effect, 199
origin, 194, 198, 206
dirt fust, 209, 240
size categories, 199
tolerance, 20
displacement cylinder, 127—32, 138
dissolved air, 190
dither control, 338, 359, 360
double acting cylinder, 127, 133-51
dual relief valve, 61
efficiencies
pump and motor, 16, 17, 156, 166—7,
173-9, 243-4, 291-2, 346
system, 43—56, 271-87
elastomer seals, 101, 128, 145, 187, 259
electrohydraulic servo valve, 338—40
electrostatic contamination, 190
electrostatic filtration, 202
energy contamination, 189
Engler, 181
entrained air, 183, 190, 252
equations of motion, 140
Euler’s strut theory, 148Index
failure
catastrophic, 198, 200
degradation, 198, 200
fault
diagnosis, 306
finding chart, 312, 315
feedback, 329-33, 338, 353, 361
filter
capacity, 202, 213, 240
construction, 206
contamination time curves, 206
cold start conditions, 205, 213, 296
electrostatic, 202
element
beta rating, 203
bubble point test, 203
changing, 211, 303
collapse pressure, 204
condition indicator, 205, 302, 314
depth type, 201, 202
flow capacity, 213
media, 201
rating 203, 207, 211, 212, 250, 296
spin-on, 211, 294
surface type, 201, 202
housing, 200
location, 47, 207—12
magnetic, 202
pressure drop through, 213
sizing, 212—3, 240
fire resistant fluid, 180, 186—7, 194, 190
filtration technology, 200
first order system, 334
flange connection, 221
flared fittings, 217—9, 223
flapper type servo valve, 339, 361
flexible separator, 192, 199, 250-1, 258-9
float switch, 251, 256
flow control
bleed off, 77
bypass, 83—5
meter in 75—88, 168, 293
meter out, 76—88, 168, 284
valves, 70 (see also Valve, flow control)
flow divider, 89—92
flow meter, 304
flow through an orifice, 70-2, 332
flow velocity, 6, 216
fluid flow, 5, 105, 237
fluids (see Hydraulic fluid)
flushing, 302
flushing valve, 170
foaming, 183, 184
form tool, 112
frequency response, 336
gas laws, 49, 257, 275
395
gaseous contamination, 190
gear motor, 156, 157
gear pump, 19, 31, 45
generated rotor (gerotor), 20, 155, 157
heat dissipation, 190, 248
heat energy, 190
high water-base fluids (HWBF), 186, 188, 189
hi-lo, 39, 63, 271
hose break valve, 231
hydraulic conduits, 214 (see also Hydraulic >
tube and hydraulic hose)
hydraulic fluids, 180
hydraulic fluid
additives, 180, 184, 185, 192
characteristics, 188
classification, 180-1
compatibility, 188
conditioners, 252
contamination, 189, 298, 304, 305, 309
contamination control, 189—213, 296
future development, 187
handling, 300
mineral oil, 181, 185, 288
oil in water emulsions (HWBF), 186, 188,
189, 252
operating temperature, 249, 252
phosphate ester, 181, 187, 190
sampling, 195, 297, 302
selection, 187
storage, 300
water glycol, 181, 186, 187
water-in-oil (invert) emulsion, 186—8
water removal, 193
hydraulic hose, 225-9
burst pressure, 226
end fittings, 227, 229
failure, 228
installation, 228, 301
selection, 228
suction, 229, 301
supports, 229, 230, 301
types, 225
working pressure, 226
hydraulic motor circuits, 163
hydraulic motors, 155 (see also Motors)
hydraulic power, 8, 9, 17
hydraulic press, 24, 39, 63, 65, 91-3, 95-7,
149
design study, 268
hydraulic stiffness, 344
hydraulic symbols, 9, 58, 63, 69, 84, 86, 87,
89, 94, 109
hydraulic tube, 214
coned fittings, 220
connections, 217—25
fittings, 217—25396
flanges, 220
flow rating, 216
installation, 224, 301
pickling, 225
staple connector, 222
weld fittings, 220
working pressures, 215
hydrocapsule, 176
hydrostatic braking, 169
hydrostatic transmissions, 62, 103, 163
characteristics, 165, 171
closed loop, 168—70, 177, 209, 319, 341
constant power, 165
open circuit, 163—8, 175
hysteresis effect, 361
inhibitors, 185
installation, 224, 301
integrated circuit, 112, 123
intensification, 90, 93, 267
intensifier, 267, 280
interfaces, 111
ISO (International Standards Organisation),
110, 181, 195, 196
international reference numbers, 110, 195
intravane, 21
invert emulsion, 186—8
isentropic expansion and compression, 50, 257
isothermal expansion and compression, 49,
WSs BIS 2S
jet pipe servo, 1, 339
JIC (Joint Industrial Council), 217, 222, 245
kickdown sequence valve, 68
kinematic viscosity, 181 (see also Viscosity)
KR tube coupling, 219
laminar flow, 6, 215, 239
land (spool), 104, 330
lap, 330, 331
Laplace, 333-8, 342—4, 349-50
last chance filter, 209
leakage coefficient, 341—4, 346-50
compensation, 263
control, 214, 234
internal, 156, 159, 168, 179, 297, 304, 341
level switch, 251, 256
linear actuators, 127
transducer, 352
liquid contamination, 192
lock valve, 87—8
logic element, 112—23 (see also Valve,
cartridge)
logic valve
pilot control sources, 119
poppet type, 113-21
remote switching, 118
spool type, 121-3
switching of multiple elements, 119
logical fault finding, 305, 308, 315—27
London Hydraulic Power Co., 253
lubrication, 101, 184—8
magnetic filter, 202
magnetic separator, 202
magnetism, 190
magnitude ratio, 337
maintenance, routine 299, 303
make-up pump, 163, 168, 320
manifold, 123, 232—4, 301
manual overrides, 107, 108
manual servo, 25—7, 179, 320, 322
mean filtration rating, 203
Index
mechanical efficiency (see Torque efficiency)
mechanical feedback, 331
mechanical servo valve, 264, 331, 336
meter in, 75—88, 168, 293
meter out, 76—88, 168, 284
microbiological contamination, 194
mineral oil, 181, 185, 288
mobile hydraulic valves, 123
arrangements, 124—6
modularized package, 113, 123
monoblock valve, 124
motion control valve, 67, 170
motor, 155
axial piston, 160
ball, 160
cam rotor, 159
characteristics, 162, 174
circuits, 163, 317, 319
circuit design examples, 172, 176
efficiencies, 166—7, 173-9, 244, 291, 346
formulae, 163—6, 244, 346
freewheel, 163, 168
gear, 156
gerotor, 157
leakage, 156, 159, 179, 341
orbit, 157
radial piston, 161—3
sizing, 290
torque, 164, 178
vane, 158
variable displacement, 158—9, 161—6
motors in parallel, 172
motors in series, 171
multi-pass test, 204
multi-pump circuits, 38—41, 46-8, 65, 271,
284, 292, 316
NFPA (National Fluid Power Association),
110, 299
NPT (National Pipe Thread), 222, 223Index 397
natural frequency, 344
needle valve, 71
neon indicators, 107
NG reference number, 111
nominal rating, 203, 206
non-return valve (see Valve, check)
notched spool, 104, 116, 352
null point, 331, 361
Nyquist diagram, 337, 338
‘O’ ring compression fittings, 219
oil cooler, 190, 192, 240, 252
oil heater, 252
oil immersed solenoid, 106
oil-in-water emulsion, 186, 188, 189, 252
oil-in-water micro-emulsion, 189
open circuit (loop) transmission, 35, 163, 167
open loop control, 329
operating temperature, 145, 249, 298, 306
orbit motor, 157
orifice flow, 70—2, 332, 358
overall efficiency, 17, 166—7, 174-6, 179,
243—4, 292, 346
overcenter valve, 65—7, 168
overlap, 331
oxidation, 189
oxidation inhibitor, 185
parallel connection, 124, 172
particle
analysis, 197
counting, 195, 298
distribution, 196—7
sizes, 195, 198, 199
particulate contamination, 194—200, 206, 297,
304 (see also Dirt)
Pascal’s laws, 4, 268
patch test, 298
phase angle, 337
phosphate ester, 181, 187, 190
pickling, 225, 301
pilot control sources, 109, 119, 271
pilot operated check valve, 94, 95, 99, 103,
112, 263, 264, 293, 309
pilot pressure unloading, 62
pilot to close check valve, 97
pipe fitting, 217—25
pipe flow, 238
pipe supports, 229, 230, 301
piston rod buckling, 147—50
piston rod ends, 146
pneumatics, 1, 42, 253
polytropic expansion and compression of a
gas, 257
poppet valves, 59, 98-100, 112—121
port identification, 11
port relief valve, 61
pour point, 183, 184
power pack, 245, 292, 301, 311
Poziflare coupling, 219
prefill valve, 95, 96, 281, 285
pressure compensation
pumps, 27, 54, 175, 272, 276, 284—6, 292
Valvester oa 4aS422 304eaS Sees 5o
pressure control cartridge valves, 120, 121
pressure control valves, 57 (see also Valve,
pressure control)
pressure drop, 103, 240
head, 5
intensification, 90, 93
line filter, 169, 208, 211, 296
losses, 240
of a liquid, 1
operated directional control valve, 107
override, 59, 62
reducing valve, 69, 70, 123
surge (damping), 262
switch, 14, 36, 52, 149, 205, 276—9, 320
zone, 19
priority flow control, 85
properties of fluids, 1
proportional amplifier, 360
proportional flow control, 358—60
pressure control, 354
pressure reducing valve, 354
pressure relief valve, 354
two stage valves, 356
versus servo valves, 340
proportional valves, 121, 123, 350
proportional valve
applications, 293, 362—6
characteristics, 351, 360
force control, 350
force, position control, 351
notched spool, 357
spool position, 353
pulsation damper, 225, 261
pump characteristics, 45, 175
delivery, 32
drives, 41
drive speed, 32
efficiencies, 16, 17, 176, 243—4, 292, 346
formulae, 15-7, 242—3, 342, 346
location, 245
noise, 33, 322
operating pressure, 30—2
selection, 30, 178, 291
servo system, 340
pump types, 15
axial piston, 22, 31, 320
centrifugal, 15
gear (external), 19, 31, 45, 46
gear (gerotor), 20
gear (internal), 19, 31398
non-positive displacement, 15
plunger, 24, 31
positive displacement, 15—35
radial piston, 24, 25
reciprocating, 22
rotary, 18
tandem, 46
Vanes 20 m2 esi
variable delivery, 21, 25-31, 41, 175, 286,
292, 302, 345, 363
pumping circuits, 35, 363
push rod, 105
quick release coupling, 230, 231
Q-pump, 33
radial piston pump, 24, 25
radial piston motor, 161—3
ramp ‘down’, 359
ramp input, 334-6
ramp ‘up’, 359
Redwood, 181
regeneration, 103
regenerative circuit, 137—9, 149
relative density, 180
relief valve, 27—9, 35, 39, 42, 58—64, 75-85,
91, 120—3, 168, 176, 270, 277, 284,
302, 309, 314, 320
ball, 59
cracking pressure, 59
cross line, 61, 167, 292, 322
differential poppet, 59, 60
direct acting, 59, 358
filter, 208
guided piston, 59
pilot operated, 59-61, 120, 122, 321
port relief, 61
remote operation, 61
selection, 62
solenoid controlled, 61, 121
unloader, 39, 62
remote switching of cartridge element, 118
reservoir
cooling effect, 248—50
design, 250—2
filling, 296-301
function, 247, 251
heater, 252
shape, 248
size, 33, 247, 249, 295
types, 247
restrictor cartridge, 116
restrictor check, 97
return line filter, 176, 208, 211, 296, 314
reusable fittings, 227
reverse flow filter, 209
Reynolds number, 239
Index
SeenEan ee EEEEEEEENEEEEEEEEESETTERS
rotary actuator (see motor)
rust inhibitor, 180, 185
safety regulations, 266
sampling valve, 297
sandwich plate (block), 61, 97, 233
Saybolt, 181
scavenging, 169, 170
seal friction, 136
seal protection, 233
sealed reservoir, 192
semi-rotary actuator, 127, 152, 236
chain and sprocket, 154
control, 155
helical screw, 155
lever arm, 154
rack and pinion, 153, 154
vane, 152, 154
sequence valve, 67—9, 282, 297
series connection, 125, 170
servo control, 25, 322, 329, 360—1, 365
servo system stability, 340
servo valve, 302, 339, 361
servo valve filter, 207, 209
sharp edged orifice, 73, 358
shear stability, 182
shut-off valve, 245, 299, 301, 315, 320
shuttle valve, 98, 169, 293
side cylinders, 282, 284
single acting cylinder, 127, 133
sinusoidal input, 336
SAE (Society of Automotive Engineers), 217,
DDNi,PD, PEM
soft seat valve, 93
soft-switching, 106, 113, 116
solenoid, 12, 106 (see also Valve, directional
control)
controlled relief valve, 61
manual override, 107
operation, 105, 351
operated cartridge valve, 117
pilot valve, 47, 53, 60, 99, 108
specific gravity, 180
spool
notched, 104, 116, 352, 357
shapes, 104
spool valve
cartridge, 113, 121-3
center condition, 102—4, 168
pressure drop, 103
stroke limiter, 109
transition states, 101, 102
standby power supply, 253, 262
standard metric cylinders, 139, 140
standards organizations, 110, 180, 217
staple connector, 222
star-delta starter, 41Index
start-up valve, 42
stop ring, 131
stop tubes, 148
strainer, 192, 207, 251, 315
streamline flow, 6, 215
stroke limiter, 74, 109
suction line filter, 207, 208, 211, 296
suction zone, 19
swaged fitting, 227
swash plate, 22, 25-31, 321
symbols, 9—14 (see Hydraulic symbols)
synchronizing valve, 89—90
synthetic fluid, 180, 187
system damping, 340
efficiency, 271—87
response, 333-8
start-up, 302, 305
stiffness, 191
tandem connection, 126
telescopic cylinder, 130—2
test equipment, 304
test points, 231, 233, 297, 299, 304, 314
thermal expansion, 184, 262
threaded connectors, 217—20, 222—4
three port flow control valve, 83, 85-6
through rod cylinder, 139
torque efficiency, 16, 17, 166—7, 243-4
transition state (valve spool), 100, 102
transmissions (see Hydrostatic transmissions)
tree branching, 314
Triple-lok® tube fitting, 217
trouble shooting, 304, 310, 314
turbulent flow, 6, 239
two stage directional control valves, 108, 112,
270, 292, 316, 356
two stage pressure control valves, 59, 70, 120,
OD. WAR, BWA, Si)
two stage sequence valve, 68, 122
underlap, 331, 361
units, 1-3, 237-8
unit step input, 331
unloader valve, 39, 62, 100
valve,
cartridge, 99, 112, 233
flow control, 122
logic element, 112—23
normally closed, 115
operation, 114
orifice, 177
pilot control sources, 119
poppet type, 113-21
pressure control, 121
pressure reducing, 123
remote switching, 118
399
restrictor poppet, 116
spool type, 113, 121-3
spool valve equivalent, 120
switching, 118—20
check (non-return), 10, 36, 39, 40, 65, 67,
71, 93, 99; 109, 1122S 12349163;
176; 2589259) 277, 299; 3ilsas22
bypass, 204, 206, 213
pilot operated, 94, 103, 112, 263, 264,
293, 309
pilot to close, 97
prefill, 95-7, 281, 285
restrictor, 97
sandwich, 61, 97, 233
shuttle, 98, 169, 293
direct acting, 101, 309
directional control, 93
identification of actuator position, 111
operators, 105
pilot operated, 107—9
poppet solenoid, 99, 112
sliding spool, 100, 112
solenoid operated, 36, 47, 101, 105, 106,
322
spool center conditions, 102—4, 168
spool stroke limiter, 109
spool transition states, 101, 102
three position, 88, 102
two stage, 108, 112, 270, 292, 316, 356
flow control 70 (see also Flow control), 209,
275, 309
bypass (three port), 83-6
deceleration, 72
divider, 89, 90
needle, 71
pressure compensated, 73—6, 83, 122, 293
priority, 85, 86
viscosity compensated, 73
mobile, 123
monoblock, 124
parallel connection, 124
series connection, 125
tandem connection, 126
valve actuation, 101, 105, 111
valve constant, 71, 332
valve interfaces, 111
valve lap, 330, 361
valve pressure control, 12, 57, 120, 121, 354
counterbalance, 64—6, 76, 95, 297, 309, 315
overcenter, 65—7, 168
pressure reducing, 69, 70, 123
relief, 58—64 (see also Relief valve)
sequence, 67—9, 282, 297
valve, servo systems, 330
valve stack, 61, 97, 232, 233
vane motor, 158, 159
vane pump, 20, 21, 31400 Index
vapor pressure, 186
vector diagram, 337
vehicle suspensions, 259, 264—5
velocity fuse, 231
velocity in pipes, 6, 7, 239
venting, 41, 61—4, 115
vent port, 60—4, 120
viscosity, 6, 73, 102, 152, 159, 181, 182,
185—9, 288
viscosity index, 181, 182, 184, 188
viscosity pressure characteristics, 182
viscosity temperature characteristics, 182
viscosity (temperature) compensation, 73, 358
volumetric efficiency, 16, 156, 166, 173-4,
177, 179, 243, 290-1
volumetric strain, 18, 183
volumetric stress, 18, 183
water-absorbing polymers, 193—4
water based fluids, 180, 186, 194
water-in-oil (contamination), 193, 300
water-in-oil (invert) emulsion, 186, 187, 188
water glycol, 181, 186, 187
water hammer, 262
water removal, 193-4
wear, 298, 309
wet pin solenoid, 105, 106
wire mesh separator, 192, 252
work done, 4, 8, 164
welded connections, 220
welded nipple, 221
wiper ring, 130, 131, 133
zero lap, 331, 332, 361
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