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`FRA]IK YEAP1E
`
`Serond Edition, Revised ond Exponded
`
`2..lcnrtlrxc sY^rrox
`
`iII
`
`Exhibit 1135
`Bazooka v. Nuhn - IPR2024-00098
`Page 1 of 8
`
`

`

`Fluid Power Design
`Handbook
`Second Edition, Revised and Expanded
`
`Frank Yeaple
`Design News Magazine
`Newton, Massachusetts
`
`,penSer
`
`by
`
`Marcel Dekker, Inc.
`
`New York and Basel
`
`Exhibit 1135
`Bazooka v. Nuhn - IPR2024-00098
`Page 2 of 8
`
`

`

`Library of Congress Cataloging in Publication Data
`
`expanded.
`
`Yeaple, Franklin D.
`Fluid power design handbook / Frank Yeaple. - 2nd ed., rev and
`p. cm. - (Fluid power and control; l0)
`ISBN 0-8247-7949-5 (alk. paper)
`l. Fluid power technology. 2. Oil hydraulic machinery - Design and
`construction. I. Tirle. Il. Series.
`TJ843.Y43 1990
`621.2-dc20
`
`B9-236i0
`CIP
`
`This book is printed on acid-free paper.
`
`Copyright @ 190 by MARCEL DEKKER, INC. All Righrs Reserved
`
`Neither this book nor any part may be reproduced or transmitted in any form or by
`any means, electronic or mechanical, including photocopying, microfilming, and
`recording, or by any information storage and retrieval system, without permission in
`writing from the pubtisher.
`
`MARCEL DEKKER, INC.
`270 Madison Avenue, New York, New York 10016
`
`Current printing (last digit):
`l0 9 8 7 6 5 4 3 2 1
`
`PRINTED IN THE UNITED STATES OF AMERICA
`
`I
`
`Hydraulic anc
`force, torque,
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`space.
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`rorque, speed,
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`Exhibit 1135
`Bazooka v. Nuhn - IPR2024-00098
`Page 3 of 8
`
`

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`Hydraullc Motors, Coupllngc' Drlvec
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`Iosses are reduced. The gear-pump drive also has some of the advantages of an eddy-
`current clutch, which include compact design and good shock absorption charac-
`teristics.
`
`HYDROSTATIC IIRIVES
`A hydrostatic drive consists of a positive-displacement pump driving a positive-dis-
`placement fluid motor, usually in one of the basic arrangements shown in Fig. 7.11.
`The pumps and motors are available in many forms, including external gear, internal
`gear, vane, radial piston, and axial piston. Each design (Fig' 7.12) with minor
`modifications can be either a pump or a motor.
`Any pump or motor can be varied in speed; for example, with a valving system
`to vary the flow to the fluid motor or with a variable-speed prime mover to drive the
`pump.
`However, only vane and piston-type pumps and motors can have variable dis-
`placement. Cear pumps have constant displacement and must be rotated at variable
`speed to adjust flow.
`Adjustable radial-piston and vane pumps and motors have movable pressure
`rings that change the eccentricity of the vanes or pistons relative to the shaft, thus
`changing the displacement. Adjustable axial-piston pumps and motors usually have
`swash plates or wobble plates that determine the effective stroke of the pistons - or
`the valve block itself can be tilted. But the principles are the same.
`Fluid motor speed is dependent on output flow of the pump divided by the
`displacement per revolution of the motor. Input torque to the pump (for a constant-
`speed electric motor) and output torque of the hydraulic motor for a given efficiency
`depend on pressure and displacement. In a positive-displacement pump-motor drive,
`pressure rises to whatever level is required to move the load at the set displacement
`
`Control
`
`Control
`
`fIXtO PUMP.
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`rlow.coilIRot vl[vr,
`roun.wtY vat-vt.
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`8u[T.til BYPTSS Vttvt
`tillxult 0R StRvo
`txTERllAt RELrtt vAl,vt
`(Pr, fl
`Pr. r)
`(Pt Mt)
`Fig.7.11 Some typical arrangements for hydrostatic drive elements.
`
`Exhibit 1135
`Bazooka v. Nuhn - IPR2024-00098
`Page 4 of 8
`
`

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`Exhibit 1135
`Bazooka v. Nuhn - IPR2024-00098
`Page 5 of 8
`
`

`

`132
`
`Hydraullc Motors, Coupllngs, Ilrlves
`
`Hydroctatlc
`
`@
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`, ,
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`=
`
`(speed) unless load torque exceeds the capacity of the fluid motor, the pump, or the
`prime mover. If the pressure exceeds the setting of any of the relief and safety devices,
`the drive slows down or stalls without damage because fluid is bypassed. As soon as
`the load returns to normal, the motor operates as before.
`The most efficient units are the piston type; vanes are slightly less efficient.
`
`Safe, Smooth Braking
`Hydrostatic drives can be slowed down and stopped more smoothly and rapidly than
`most other drives. This is due in part to the overload capability of the fluid motor.
`There are two other important reasons: (l) The fluid motors are smaller and have con-
`siderably less inertia than equivalent electdc motors, eddy-current clutches, or mechan-
`ical drives. (2) The motive fluid is easy to control or restrict at any of several flow
`points.
`Two inherent braking systems are ideal for fluid drives: regenerative and dy-
`namic.
`With regenerative braking, the inertia of the driven machinery begins to drive
`the fluid motor as a pump, which in turn drives the pump as a motor. The kinetic
`energy is quickly absorbed, stopping the fluid motor and its connected equipment.
`ln dynamicbtakhg, flow from the pump to the fluid motor is cut off by a valve.
`Load inertia drives the fluid motor as a pump, and the output is forced through a
`relief valve, creating a cushioned braking effect.
`Conventional external braking with a friction clutch is often used, usually on
`the driven machinery. Inherent and external braking are combined in some applica-
`tions. One example is a hydraulic-powered winch, in which regenerative braking
`action is supplemented by a friction brake to hold the load.
`
`Adjusting th€ Displacement
`There are many conventional ways to change the position of the yoke or stroking ring
`of adjustable-speed pumps and motors, including hydraulic, pneumatic, electric, and
`mechanical. The pressure compensator (Fig. 7.13) is of particular interest because it
`is a feedback system in itself.
`The pressure compensator refers lo a control feedback device that senses pres-
`sure in the line to the fluid motor and uses it to adjust pump or motor displacement
`to correct or improve the existing operating conditions (compensate).
`This pressure signal is useful for a variety of reasons. For a fixed-displacement
`fluid motor, you can determine torque by reading a pressure gage. And you can use
`the pressure as a feedback signal to reduce pump delivery, hence speed, if this has
`raised torque abow a preset maximum.
`ln fig. 7.13, the compensator is attached to the pump control, A. Hydraulic
`pressure is applied at the upper port. If pressure - representing torque-exceeds the
`setting of pilot valve screw F, the pump displacement is reduced until the torque
`returns to normal.
`Initial pressure is below the minimum setting of the compensator. Spring B ex-
`tends piston A for maximum pump displacement. Hydraulic pressure at R acts through
`orifice X and passage V to impose a thrust on spool H. Piston A remains extended
`when this pressure cannot overcome spring G to shift spool H.
`When the pressure reaches the setting of pilot valve screw F, spool H shifts to
`
`Exhibit 1135
`Bazooka v. Nuhn - IPR2024-00098
`Page 6 of 8
`
`

`

`Hydrostatic Drlvec
`
`133
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`rol H shifts to
`
`Exhibit 1135
`Bazooka v. Nuhn - IPR2024-00098
`Page 7 of 8
`
`

`

`134
`
`Hydraulic Motors, Coupllngs, Drlves
`
`direct fluid from chamber Q and passage V through interconnected holes N of spool
`H to chamber Y. This chamber is connected to drain through orifice Z and to the
`annulus area of piston A through hole W of piston J and passage U. Flow through
`orifice X causes a pressure drop so that the pressure in chamber R becomes greater
`than in chamber Q. The pressure difference unseats piston J, and fluid is throttled
`from chamber R to passage U. Fluid in U moves piston A to decrease pump delivery
`until it equals system requirements.
`The pressure compensator can also be mounted on a variable-displacement fluid
`motor. By adjusting motor displacement, you can change its speed to cope with a load
`change, holding the same hydraulic pressure as before. Thus speed is decreased as
`a function of load.
`
`Hydrostatic-Drive Classifications
`The drives shown in Fig. 7.1I can be further classified in the following five standard
`categories, all based on flow (Fig. 7.14).
`
`PF-MF (varioble-speed prime mover). Fixed-displacement pump, fixed-displacement
`motor; motor speed adjusted by varying the speed of the prime mover (electric motor
`or internal-combustion engine) to control pump output.
`Prime mover characteristics and not pump-motor performance are involved here,
`
`PF-MF (with flow-control yalves). Fixed-displacement pump, fixed-displacement
`motor; motor speed adjusted with valving that controls the input or output flow of
`the motor.
`In its simplest form the PF-MF (valved) is the lowest in cost of all hydrostatic
`drives. Efficiency is relatively low because control is by throttling, but there are many
`important uses for this basically simple drive. Several arrangements are described in
`detail under flow-control valves in a following section.
`
`PF-MV. Fixed-displacement pump, variable-displacement motor; motor speed ad-
`justed by changing the effective stroke of the pistons or vanes (gears not applicable).
`This arrangement, and the PV-MF and PV-MV arrangements following, have
`well-defined characteristics.
`In the PF-MV drive, torque decreases as speed increases, useful for driving a
`roll (Fig. 7.15) that winds paper or other lveb material. As the roll diameter in-
`creases, rotational speed must decrease to hold a constant linear velocity of the
`paper. At the same time, mass and resisting torque of the roll increase, matching the
`PF-MV performance characteristics.
`Motor displacement is gradually increased by the control to reduce motor speeo.
`The speed drops because the motor takes more fluid per revolution. Motor torque
`rises because the effective moment of the vanes or pistons is increased. The horse-
`power remains relatively constant over the entire speed range.
`Using the constant torque driye described below would be uneconomical here
`because in such a drive the motor would have to be sized to withstand maximum torque
`at maximum speed-yet it would not normally run at that point.
`For example, suppose the load has a torque of 40 lb-ft at 300 rpm and l0 lb-ft
`at 1200 rpm. A constant-torque drive would have to be sized to produce 40lb-ft and
`
`Hydrostatlc I
`
`:: .rsrable
`
`Fig.7.l4 St
`
`Exhibit 1135
`Bazooka v. Nuhn - IPR2024-00098
`Page 8 of 8
`
`