Case 1:17-cv-00770-JDW-MPT Document 120-3 Filed 11/17/22 Page 1 of 15 PageID #:
`13122
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`EXHIBIT P
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`Case 1:17-cv-00770-JDW-MPT Document 120-3 Filed 11/17/22 Page 2 of 15 PageID #:
`13123
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`INTE.RNATION.All
`
`Characteristics of Multiple Range Hydromechanical Transmissions
`Author(s): Eli Orshansky and William E. Weseloh
`Source: SAE Transactions, 1972, Vol. 81, SECTION 3: Papers 720447–720743 (1972), pp.
`2153-2165
`Published by: SAE International
`
`
`
`Stable URL: https://www.jstor.org/stable/44722865
`
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`Case 1:17-cv-00770-JDW-MPT Document 120-3 Filed 11/17/22 Page 3 of 15 PageID #:
`13124
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`720724
`
`Characteristics of Multiple Range
`Hydromechanical Transmissions
`
`Eli Orshansky
`Orshansky Transmission Corp.
`
`William E. Weseloh
`Rohr Industries
`
`IN ORDER TO compete successfully with the commercially
`established devices for power transmission, any new device
`which expects to penetrate the market to a large extent must
`provide some advantages which are not obtainable with the
`conventional devices.
`Hydromechanical transmissions must offer something to
`the user which is an improvement over devices currently
`available. What can a hydromechanical transmission offer that
`othersoannot, and what does it mean to the user? Hydro(cid:173)
`mechanical transmissions can be efficient and practical, in(cid:173)
`finitely variable devices offering the capability of optimizing
`for minimum exhaust emissions, maximum fuel economy, or
`maximum power availability.
`Advantages to be gained by using infinitely variable hydro(cid:173)
`mechanical transmissions lie in the fact that the powerplant
`and transmission can be considered as one system, and pro(cid:173)
`grammed to operate under the most advantageous condi(cid:173)
`tions. The optimizing benefits can only be realized if the
`transmission has high efficiency.
`The hydromechanical transmission is a split-power-path type
`device which transmits a portion of the power through a
`direct mechanical path, and a portion of the power through
`positive displacement hydraulic motor pumps. The portion
`of power transmitted hydraulically is determined by the gear(cid:173)
`ing configuration and by adjusting the displacements of the
`
`-----------------------------------ABSTRACT
`
`The purpose of this paper is to show the advantages of
`multirange hydromechanical transmissions and to show some
`basic relationships of primary design parameters. Hydro(cid:173)
`mechanical transmissions can be designed so that they main(cid:173)
`tain a high efficiency over a wide range of torque/speed
`variations. The amount of volumetric loss and, therefore,
`
`hydraulic units. Ratio change is accomplished by adjusting
`the relative displacements and, therefore, the relative speeds
`of the hydraulic units. The ratio of output speed va_riation
`available through a single gear train is a function of the amount
`of power which can be transmitted hydraulically. Decreased
`hydraulic power results in decreased range per gear train and,
`therefore, a larger number of gear trains are required to
`achieve a given overall speed and torque variation for the
`transmission.
`There are tradeoffs between the improved efficiency and
`system capability of increased number of ranges on the one
`hand, and its increased complexity on the other. The more
`ranges there are, the more planetary gearing and clutches are
`required. Also, the more ranges there are, the more compli(cid:173)
`cated the controls become. At the same time, the loads on
`gears and bearings decrease, and the size and/or stress level of
`the hydraulic units can be reduced.
`It can be shown that a hydromechanical transmission can
`be constructed having gearing and clutch complexity similar
`to a corresponding powershift transmission.
`
`COMPARISONS
`
`For a qualitative comparison, it can be said that for a multi(cid:173)
`range transmission, the gear and clutch section will compare
`
`slip, can be reduced to a minimum; therefore, it is possible to
`control the speed of the powerplant by proper ratio control.
`The powerplant and transmission can be considered as one
`system which is permitted to operate, under optimum condi(cid:173)
`tions, irrespective of the road load or speed of the vehicle.
`
`This content downloaded from
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`Case 1:17-cv-00770-JDW-MPT Document 120-3 Filed 11/17/22 Page 4 of 15 PageID #:
`13125
`
`2154
`
`ELI ORSHANSKY AND W. E. WESELOH
`
`in cost to that of a powershift transmission having a similar
`number of ranges. The controls will also be similar in cost.
`The relative cost of the multirange hydromechanical and a
`powershift transmission will, therefore, depend on the cost
`of the two hydraulic units, as compared to a torque converter
`assembly, with its attendant overrunning clutch and lockup
`clutch.
`The increase in first cost must be offset by more advan(cid:173)
`tageous system capability. Some of these advantages are:
`ENGINE SPEED CONTROL - Being infinitely variable and
`virtually without internal slip, it is possible to program the
`transmission system so that the engine operates at constant
`speed or at some number of preselected speeds which can be
`varied in accordance with the vehicle power demands. For
`example, a truck system can be programmed to operate the
`engine at some lower speed during city and cross-country flat(cid:173)
`land operation and at rated speed when maximum power is
`required by the vehicle, such as in mountainous operations. A
`further refinement of the control system can provide for
`variation in the transmission ratio such that the engine is
`operated at whatever speed will give the maximum fuel
`economy and/or minimum emissions for that particular
`combination of vehicle speed and power demand. This
`ability to program engine speed basically independent of
`vehicle speed is a benefit afforded by none of the previously
`existing transmission types.
`NO INTERRUPTION IN POWER FLOW -As all range
`changes are stepless and conducted with overlapping clutch
`sequencing ( on-going clutch engages prior to disengaging off(cid:173)
`going clutch), there is no interruption in power transmission
`to the vehicle drivetrain. Not only does this increase drivetrain
`component life by removing the shock loads imposed by the
`absorption of engine inertia during shifts, it also frees the
`vehicle operator from all of the problems associated with
`rapid variation in torque application during inclement weather
`conditions. This feature also allows maximum grade start-ups
`without vehicle roll-back. In fact, the operator can hold the
`vehicle at rest on a grade without utilizing the service brakes
`(assuming adequate drive wheel traction) with the engine at
`idle, due to the infinite ratio feature of the system. In this
`condition, there is virtually no power requirement on the
`engine other than that created by the transmission boost
`pump which is utilized for lube and control functions. Often(cid:173)
`times, torque converter/powershift transmissions are utilized
`for holding the vehicle on a grade, but the adverse effect
`created by the attendant generation of heat is a well-known
`problem to transmission manufacturers.
`FULL ENGINE BRAKING - Maximum engine friction can
`be obtained for vehicle braking regardless of vehicle speed
`simply by programming the transmission system to main(cid:173)
`tain maximum engine speed during the periods of closed
`throttle operation.
`AUXILIARY BRAKING - Auxiliary braking may be
`achieved by. the partial application of nonsychronous
`clutches. This requires substantial heat rejection capability
`and increases the controls complexity.
`
`OPERATIONAL CAPABILITIES
`
`The operational capabilities can provide additional advan(cid:173)
`tages unique to the type of engine system employed.
`DIESEL ENGINES -The high cost and complexity of
`diesel engine fuel systems today are due, in large part, to
`engine manufacturers' increasing requirements for additional
`control features, such as torque shaping, variable advance,
`and aneroid fuel limiting. If the engine is required to operate
`only at one or two speeds, however, these features can all be
`greatly simplified or, in most cases, eliminated, with virtually
`no sacrifice in engine performance or emissions.
`On turbocharged engines, the benefits of limiting the operat(cid:173)
`ing speed range are even greater. Not only will the turbo(cid:173)
`charged acceleration lag be greatly reduced but the turbo(cid:173)
`charger can be matched so as to operate at a much higher
`efficiency than is possible when it is required to operate over
`the entire engine speed range.
`Many of the compromises presently necessitated in engine
`design, such as valve timing, vibration damping, and combus(cid:173)
`tion chamber design, can also be greatly reduced by the
`application of a transmission system which will reduce the
`operating speed requirements.
`TURBINE ENGINES - The major advantage obtained when
`coupling a turbine engine to this type of transmission system
`is that the required complexity and, therefore, cost of the
`turbine and controls are greatly diminished. A single shaft
`turbine becomes feasible for vehicle motive power which, in
`addition to reducing engine complexity, provides some major
`operational advantages. Prime among these is the ability to
`obtain engine braking at a power level in excess of the engine
`rating. Operational economy can be improved by program(cid:173)
`ming the transmission control for a predetermined schedule
`of turbine-operation conditions. Since the transmission is
`capable of controlling the speed of the engine, the fuel con(cid:173)
`trol problems are still further simplified.
`KINETIC ENERGY DEVICES - Recent studies have indi(cid:173)
`cated that kinetic energy propulsion systems have advantages
`in mass transportation vehicles. These systems require an
`infinitely variable, high-efficiency transmission for practicality.
`Such requirements can be met with multirange hydromechani(cid:173)
`cal transmissions.
`SYSTEM EFFICIENCY -To accomplish the advantages
`just described, the transmission must have a high efficiency
`so that the potential gains in overall system performance are
`not offset by internal losses. Although it is unlikely that any
`transmission which circulates power hydraulically will ever be
`as efficient as a straight mechanical transmission, the over-
`all engine/transmission system can be made more efficient
`due to the improved operating conditions afforded the engine
`by the infinitely variable transmission system, provided the
`transmission efficiency remains sufficiently high throughout
`the majority of the vehicle-operating ranges.
`Since the efficiency of a hydromechanical transmission de(cid:173)
`pends primarily on the percentage of power transmitted
`hydraulically, it must be kept to a minimum.
`The mathematical relations governing torque and speed
`
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`

`Case 1:17-cv-00770-JDW-MPT Document 120-3 Filed 11/17/22 Page 5 of 15 PageID #:
`13126
`
`HYDROMECHANICAL TRANSMISSIONS
`
`2155
`
`variation are such that the quantity of hydraulic power trans(cid:173)
`mitted is a function of ratio, and increases very rapidly with
`a small increase in ratio. In order to limit the quantity of
`hydraulic power for a required overall torque and speed ratio,
`the transmission must go through several narrow speed and
`torque variation ranges, with synchronous shifts between
`ranges to accomplish a stepless variation over the entire
`range.
`For minimum percent of hydraulic power:
`I. Each of the several ranges must be equal in ratio. With
`a given overall torque variation consisting of "n" ranges, each
`range has to be
`
`to the input, rotates at zero displacement, and, therefore,
`prevents the rotation of the fixed displacement unit by block(cid:173)
`ing its fluid output.
`The power is transmitted entirely by the mechanical path.
`The gear loads and torques which are produced within the
`planetary assembly are, therefore, a function solely of en(cid:173)
`gine torque and planetary ratios. No torque is added or sub(cid:173)
`tracted hydraulically.
`The recirculative mode results in planetary gear loads and
`torques which are higher than those produced by the engine,
`and the nonrecirculative mode results in gear loads and
`torques which are lower than those produced by the engine.
`
`(I)
`
`RECIRCULATIVE MODE
`
`2. The shift from one range to another must occur under
`synchronous conditions, without interruption of power
`flow.
`3. The design must be such as to avoid overspeeds of gears,
`particularly planet pinions.
`NOISE LEVEL REDUCTION - An area which is receiving
`more attention due to increasingly stringent government regu(cid:173)
`lations is the noise level of any proposed transmission system.
`The noise produced by hydrostatic transmissions and, to a
`lesser degree, hydromechanical transmissions, is almost wholly
`due to the hydraulic system. The noise level varies as a func(cid:173)
`tion of the load under which the hydraulic system operates.
`It is apparent that for any transmission system utilizing
`hydraulic power, the noise level is a function of the amount
`of power transmitted hydraulically. With hydrostatic and
`hydromechanical transmissions which transmit a high per(cid:173)
`centage of power hydraulically, it is not feasible to operate
`the hydraulic unit at moderate ratings, nor is it feasible to
`tolerate any reduction in efficiency. On the other hand,
`multirange hydromechanical transmissions may be operated
`at moderate ratings with little penalty in efficiency.
`A great many combinations of hydraulic systems and plane(cid:173)
`tary assemblies can be conceived to produce the desired speed
`and torque variation. It is beyond the scope of this paper to
`evaluate the relative merits of the hundreds of combinations
`which have appeared in the patent and technical literature
`during the past 80 years or so.
`This discussion will be limited to one particular type of
`planetary/hydraulic combination which permits the use of
`small-size hydraulic units, and affords the simplest possible
`starting and reverse conditions.
`Before going ahead with the description of the three-range
`transmission, it seems desirable to review the general prin(cid:173)
`ciples and nomenclature underlying power-splitting trans(cid:173)
`missions.
`The definition of terms and mathematical relationships are
`herein described.
`
`LOCKED REACTION MODE
`
`In this mode of operation, there is no power transmitted
`hydraulically, because the variable unit, which is connected
`
`During the interval when the power is transmitted in a re(cid:173)
`circulative manner, the entire engine power is delivered to the
`planetary. The fixed hydraulic unit, which is connected to
`the reaction member, now acts as a pump. It delivers hy(cid:173)
`draulic power to the variable unit, connected to the input
`upstream of the planetary, which now acts as a motor.
`Therefore, the hydraulic system adds power to the input of
`the planetary. This results in increased output torque, and,
`at the same time, the gear and bearing loads within the plane(cid:173)
`tary are increased above the level produced by engine torque.
`Thus the planetary system internally recirculates more than
`the engine input horsepower. Specifically, this equals the
`engine horsepower plus the percentage of power recirculated
`to the input hydraulically. The sum of the losses in both
`systems is therefore greater, and the overall transmission ef(cid:173)
`ficiency during this mode of operation is lower than during
`the nonrecirculative mode now described.
`
`NONRECIRCULATIVE MODE
`
`During the interval when the power is transmitted in a non(cid:173)
`recirculative manner, the total power is divided by the plan(cid:173)
`etary into power transmitted by the mechanical system, and
`power transmitted by the hydraulic system. Thus, the me(cid:173)
`chanically transmitted power is less than 100%, and the
`balance is transmitted hydraulically.
`The variable hydraulic unit, which is connected to the in(cid:173)
`put upstream of the planetary assembly, acts as a pump in
`this mode of operation, and absorbs some of the input horse(cid:173)
`power; and the fixed hydraulic unit, which is connected to
`the reaction member of the planetary, acts as a motor and
`adds power to the output of the planetary.
`The gear and bearing loads in the planetary assembly are,
`therefore, less than those produced by the engine torque,
`since the torque is divided into a mechanical and hydraulic
`path before it reaches the planetary.
`Hydrostatic Range - RH. All power is transmitted hydrau-
`lically. Power-splitting planetary operates in a locked condi(cid:173)
`tion and is disconnected from the engine. This is torque(cid:173)
`limited range, during which the transmission delivers the
`maximum torque beyond which the wheels will slip. During
`the constant-torque operation, the horsepower which can be
`
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`Case 1:17-cv-00770-JDW-MPT Document 120-3 Filed 11/17/22 Page 6 of 15 PageID #:
`13127
`
`2156
`
`ELI ORSHANSKY AND W. E. WESELOH
`
`transmitted by the wheels, therefore, increases from zero at
`the start of RH to 100% of engine power at the end of RH.
`Total Hydromechanical Range - RHM· Power transmitted
`by a combination of mechanical and hydraulic means. RHM
`may consist of several ranges, R, which may have equal speed
`and torque variation ratio. R equals the range of output
`torque and speed variation, during which the variable hy(cid:173)
`draulic unit goes from full displacement in one direction, to
`zero, and over center to full displacement in the other direc(cid:173)
`tion.
`The planetary reaction unit goes simultaneously from
`maximum speed in one direction, to standstill, and then to
`maximum speed in the other direction. Each range is fur(cid:173)
`ther divided into two subranges:
`
`(2)
`
`where:
`
`Subrange RR = recirculative, power transmitted by recir(cid:173)
`culation of hydraulic power
`Subrange RNR = nonrecirculative, power transmitted by
`dividing load between mechanical and hy(cid:173)
`draulic system.
`Relation of Mechanically and Hydraulically Transmitted
`Portions of Power - The power relations in the recirculative
`mode are:
`
`Output speed at end of RR
`X
`-R - Output speed at start of RR
`
`(3)
`
`Total power circulated mechanically within the planetary,
`including recirculating power:
`
`(Input hp) (xR)
`
`Power recirculated hydraulically within the planetary:
`
`(Input hp) ( XR - 1)
`
`The power relations in the nonrecirculative mode are:
`
`Output speed at end of RNR
`X
`-
`NR - Output speed at start of RNR
`
`Power transmitted hydraulically:
`
`( XNR -1)
`(Input hp) XNR
`
`Power transmitted mechanically:
`
`(Input hp)
`
`( XNR -1)
`I - XNR
`
`The maximum power requirement of the hydraulic system
`is, therefore:
`
`(9)
`
`At midrange, theoretically, zero horsepower is transmitted
`hydraulically.
`
`A multirange transmission of three hydromechanical ranges
`is shown in Fig. 1.
`In order to simplify the description of the functions of
`this device, we will start from point A in Figs. 2 and 3. This
`mode is the locked reaction mode and occurs at point A
`when the variable unit is on zero displacement and, there(cid:173)
`fore, locks the ring gear against rotation in each range. At
`this point, the output has a speed as indicated by point B,
`and the entire power is transmitted mechanically.
`The gear and bearing loads are, therefore, a function of
`engine torque and planetary gear ratios, and the entire power
`is transmitted mechanically.
`Since it is desired to vary the output speed, while retaining
`a constant input speed and horsepower, it becomes necessary
`to add torque to the planetary when the speed of its output
`member is decreased with respect to point B, and subtract
`torque from the planetary when its output speed is increased
`with respect to that point, because the gearloads within the
`planetary have a constant relation with respect to each other.
`Thus, if we wish to increase the torque and decrease the
`speed of the output carrier, the displacement of the variable
`hydraulic unit is increased from zero in a direction which
`allows the planetary reaction unit (which is shown as a fixed
`displacement unit in the schematics) to rotate under the in(cid:173)
`fluence of the drive reaction, and act as a pump.
`It supplies fluid under pressure to the variable input unit,
`which acts as a motor, thus adding its torque to the input
`shaft. The input shaft now transmits not only the engine
`torque, but also the added hydraulic torque to the planetary,
`which for this reason operates at a higher level of load than
`at point A, and the carrier output torque, therefore, in(cid:173)
`creases with its decrease in speed.
`As the displacement of the variable input hydraulic unit is
`further increased, the planetary reaction unit increases its
`speed, the carrier output speed decreases, and its torque
`increases.
`The increase in planetary gear loads causes an increase in
`the output carrier torque (Fig. 2). During this time, the
`power transmitted by the hydraulic system from the reaction
`to the input is recirculated within the planetary. This mode
`of operation is, therefore, called the recirculative mode, and,
`due to the simultaneous rise in pressure, displacement of the
`variable input unit, and speed of the fixed planetary reaction
`unit, it is possible to recirculate more than the input horse(cid:173)
`power. This is solely a function of the ratio RR in the def-
`inition of terms. As this ratio increases, the size of the hy(cid:173)
`draulic unit increases very rapidly, and the efficiency
`deteriorates.
`In going to higher output speed from the locked reaction
`
`( 4)
`
`(5)
`
`(6)
`
`(7)
`
`(8)
`
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`

`Case 1:17-cv-00770-JDW-MPT Document 120-3 Filed 11/17/22 Page 7 of 15 PageID #:
`13128
`
`HYDROMECHANICAL TRANSMISSIONS
`
`2157
`
`VARIABLE
`~~;;;;;. .... ~3-;;;;;.~;;;;-~-- DISPLACEMENT
`
`--+
`
`100
`
`FIXED
`DISPLACEMENT
`UNIT
`
`Fig. 1 - Three-range transmission
`
`z
`0
`j::
`" ~
`!!:: ...
`
`...J 6
`
`...J
`:::)
`::;;
`w
`:::)
`
`4
`
`75 ~
`0 ...
`
`50
`
`25
`
`so
`
`100
`
`R
`
`R
`
`10
`
`30
`
`20
`A
`
`50
`
`40
`;,.
`
`% OUTPUT SPEED
`
`Fig. 2 - Three-range transmission - horsepower and
`torque at rated input
`
`Cl z
`;:::
`'.5
`:::,
`... u
`:::)
`IC
`Q. !i!
`z
`u. z
`0 ~
`...
`Cl z
`
`IC
`
`;:::
`"
`5
`u
`a: u
`"' a:
`
`0..
`J:
`
`point, the variable input unit is stroked in the opposite direc(cid:173)
`tion and becomes a pump, thus absorbing some of the input
`torque, and drives the fixed planetary reaction unit which
`now acts as a motor to increase the speed of the output car(cid:173)
`rier. The level of gearloads in the planetary is reduced with
`respect to these values at the locked reaction point.
`As the displacement of the variable input unit is increased,
`the speed of the fixed planetary reaction unit and the output
`is also increased, until it reaches its maximum design speed in
`that particular range.
`Since the power is divided upstream of the planetary, no
`
`recirculation takes place, and this mode is, therefore, called
`the nonrecirculative mode, RNR
`
`The multirange transmission makes it possible to use the
`efficient part of the variable planetary/hydraulic device over
`several ranges by synchronous shifts between the ranges. As
`a result, the efficiency is maintained throughout a wide
`torque/speed variation, and the size of the hydraulic units
`is considerably reduced.
`
`Fig. 4 shows a comparison of sizes of hydraulic units and
`horespower transmitted hydraulically for transmissions of
`
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`

`Case 1:17-cv-00770-JDW-MPT Document 120-3 Filed 11/17/22 Page 8 of 15 PageID #:
`13129
`
`2158
`
`120
`
`ELI ORSHANSKY AND W. E. WESELOH
`
`{/)
`
`100
`
`a:
`w
`a,
`:;;
`w
`:;;
`>- f-
`:::,
`a:
`.,: Cl.
`f- ~ 40
`w
`z
`.,:
`.J
`Cl.
`
`80
`
`60
`
`LL.
`0
`
`?,o
`
`LL.
`0
`0
`w
`w
`Cl.
`{/)
`
`40
`
`BO
`
`RANGE I
`R
`
`RANGE II
`R
`
`RANGE Ill
`R
`
`10
`
`20
`
`30
`
`40
`
`50
`
`60
`
`70
`
`BO
`
`90
`
`100
`
`% OUTPUT SPEED
`
`Fig. 3 - Three-range transmission - speeds of
`planetary elements at maximum input speed
`
`400
`
`300
`
`200
`
`100
`
`f-:::,
`0..
`~
`LL
`0
`
`0
`
`Cl.
`I
`S!
`_J
`:::,
`.,:
`a:
`0
`>-
`I
`
`Table 1 - Specifications
`
`Input, hp
`Input, rpm
`Torque multiplication ratio
`Maximum output speed, rpm
`Speed variation, rpm
`Forward
`Low speed, reverse
`High speed, reverse
`
`350
`2400
`8.6: I
`2800
`
`0-2800
`0-350
`0-1540
`
`Table 2 - Ratios
`
`ONE
`RANGE
`
`TWO
`RANGES
`
`THREE
`RANGES
`
`2.13
`1.565 max recirculated hydraulic hp, 56.5%
`1.36 max nonrecirculated hydraulic hp, 26.5%
`1.18 at top speed, nonrecirculated hydraulic hp, 15.3%
`
`RNR
`
`~ MAXIMUM RECIACULATIVE
`
`I MAXIMUM NON-AECIACULATIVE
`
`HP
`
`HP
`
`Fig. 4 - Hydraulic horsepower as a percent of input power. Transmis(cid:173)
`sion of various ranges, overall ratio 8.6: 1
`
`various number of ranges while maintaining an overall ratio
`of 8.6: l at full horsepower.
`Table l gives a description of the specifications of a typical
`three-range transmission. Transmission consists of hydro(cid:173)
`static range and three hydromechanical ranges. For optimi(cid:173)
`zation of performance at maximum speed, the last subrange
`RNR is shortened so that RHM = 8.25 and the last RNR =
`1.18, as shown in Table2.
`In starting from standstill, or in reverse, the transmission
`
`operates in a hydrostatic mode. Two output speeds are
`available. In the low-speed hydrostatic range, the engine
`drives gear 1, which drives the variable displacement unit act(cid:173)
`ing as a pump through gear 2. Clutch Dis disengaged; thus,
`no mechanical drive is transmitted to the planetary by gear
`6. The fluid under pressure is delivered to the fixed unit,
`acting as a motor, which drives the planetary assembly
`through gears 3 and 4. Clutch Eis engaged, and locks ring
`gear 10 to carrier C 1, tl}us locking the en tire planetary as-
`sembly against relative rotation. The planetary rotates as
`one part, and drives sun gear 14, which drives the output car(cid:173)
`rier c3 at reduced speed, because clutch C, which is engaged,
`holds ring gear 16 against rotation.
`The output, therefore, operates at low speed and maximum
`
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`
`

`

`Case 1:17-cv-00770-JDW-MPT Document 120-3 Filed 11/17/22 Page 9 of 15 PageID #:
`13130
`
`HYDROMECHANICAL TRANSMISSIONS
`
`2159
`
`VARIABLE
`
`DISPLACEMENT
`
`• • • • •
`
`:-._:
`
`. C
`
`Mechanical -
`
`-
`
`_,.._
`
`-
`
`Hydraulic
`
`••._.,.••••
`
`• ;
`....
`•
`
`FIXED
`
`DISPLACEMENT
`
`UNIT
`
`Fig. 5 - Three-range transmission - hydrostatic range, low speed
`
`torque. Starting from zero output speed, the displacement
`of the variable unit is increased from zero in either direction,
`and the speed of the output shaft varies proportionately to
`the displacement in either direction (Table 3 and Fig. 5).
`If it is desired to operate at higher reverse speed in hydro(cid:173)
`static range, the drive is not taken through gear 14, but in(cid:173)
`stead through carrier c2 and clutch B. This eliminates the
`reduction afforded by the planetary, which consists of gears
`14-16, and drives the output shaft directly at reduced torque
`(Table 4 and Fig. 6).
`When the speed in low-hydrostatic range reaches its maxi(cid:173)
`mum, and it is desired to go to higher output speed, the
`transmission shifts from hydrostatic to first hydromechanical
`range. At the top speed in the hydrostatic range, the locked
`planetary assembly reaches a speed such that it is possible to
`engage clutch D at synchronous speed, and immediately
`thereafter disengage clutch E. The transmission now is in
`the recirculative portion RR, of the first hydromechanical
`range R. There is no change in the displacement of the vari(cid:173)
`able unit in either magnitude or direction.
`As soon as clutch D is engaged, and E is disengaged, there
`is a reversal in function of the hydraulic units. The fixed
`unit, which has been a motor heretofore, now becomes a
`pump, and the variable unit which has been a pump, now
`becomes a motor. However, the rotation of the hydraulic
`units is in the same direction as previously, thus, there is a
`reversal of pressure in the hydraulic lines, but no change of
`displacement of the variable unit.
`The fixed unit now becomes a pump, and recirculates
`power to the variable unit, which now is a motor. Thus, the
`variable planetary system is subject not only to the input
`power provided by the engine, but also to the added power
`recirculated by the hydraulic system to the input gear 7.
`The level of gear loads is raised in the planetary above that
`
`Table 3 - Hydrostatic Range, Low Speed*
`
`Clutches
`A B C D E
`
`- On
`
`- On
`
`Ranges
`
`Hydrostatic, low speed
`Hydrostatic, high speed, reverse
`I, hydromechanical
`II, hydromechanical
`III, hydromechanical
`
`*See Fig. 5.
`
`imposed on it by the engine, and the output torque at gear
`14 is, therefore, at a maximum.
`To increase the speed of the output shaft, the variable hy(cid:173)
`draulic unit is reduced in stroke which results in a decrease
`of speed of the fixed unit and, therefore, an increase of
`speed of the output shaft. This also reduces the amount of
`power recirculated by the hydraulic system, as shown in Fig.
`2, and, therefore, less power is added to the input by the
`variable unit. Obviously, as the output speed increases, the
`output torque decreases.
`Finally, the stroke of the variable unit is reduced to zero,
`which hydraulically locks the fixed unit against rotation. At
`. this point, the locked reaction mode is reached. Now power
`is recirculated, and the gear loads within the variable plan(cid:173)
`etary are produced solely by the engine input (Table 5 and
`Fig. 7).
`In order to increase the output speed further, the variable
`displacement unit is stroked in the opposite direction. The
`pressure remains in the same passages as in the recirculative
`mode previously described, but the flow changes direction.
`Thus, the variable unit becomes a pump, and the fixed unit
`
`This content downloaded from
`(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)141.211.4.224 on Wed, 09 Mar 2022 22:17:30 UTC(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)
`Al