Motor Eaton 3933 4633 5433 6433 7630                               Pump Eaton 3923 4623 5423 6423 7620 7640

Eaton ACA Pump Technical Data  
Table of values (theoretical values)   

Eaton ACA pump		Eaton 3923	Eaton 4623	Eaton 5423	Eaton 6423	Eaton 7620
Displacement	in3/rev	3.89	4.6	5.44	6.44	7.62
	cm3/rev	63,7	75,3	89,1	105,5	124,8
Maximum Shaft Speed	Rpm @ 18°	4160	4160	3720	3720	2775
Nominal Pressure	psi	6000	6000	6000	6000	6000
	(bar)	(420)	(420)	(420)	(420)	(420)
Peak  Pressure	psi	7000	7000	7000	7000	7000
	(bar)	(480)	(480)	(480)	(480)	(480)
Output  Flow	g/m @3500 psi	67.3	79.2	84.1	99.1	87.9
	l/m @241 bar	255	300	318	375	333
Input Torque	lb-in @3500 psi	2346	2786	3285	3900	4552
	Nm @241 bar	265	315	371	441	514

Eaton heavy duty variable pump
The Eaton heavy duty variable displacement pump contains a rotating cylinder barrel and pistons. The displacement control directs control pressure to the two servo pistons that position the swash plate. The variable pump is powered into stroke and springs, on the servo pistons, bring it out of stroke. The swash plate pivots on tapered roller bearings. A bolt-on charge pump, with a cartridge type charge pressure relief valve, is available in four displacements. One lever controls direction, varies speed and provides dynamic braking. This ease of operation, in conjunction with a wide variety of control options, allows Eaton hydrostatic transmissions to be readily adapted to many applications.
Power Limiter Valve Operation
Power limiter valves (PLV) are high pressure relief valves built into the pump’s end cover. When pressure in the high pressure loop gets too high, the PLV opens to the pump case. Besides an immediate drop in the loop high pressure, the open PLV also causes control pressure to drop. This in turn allows the centering springs on the servo pistons to bring the pump out of stroke until the pressure drops to the relief valve setting and the PLV closes. The PLV will also act as a check valve to prevent cavitations in the event of a rapid pressure rise and hose expansion. A motor with integral shuttle valve is used in conjunction with the power limiter valve pump.
Tandem Pump Applications
Tandem pumps are most typically used in applications where two independent sources of hydraulic power are required while taking advantage of using only one power source to drive the two pumps. This saves on the expense of driving two pumps by eliminating the split drive gear box or eliminating another power source such as a second engine or motor. Tandem pumps can be used on machines such as track drive equipment where independent power is required at each track. Speed and power can be controlled to each side of the vehicle for steering and vehicle speed control both in forward and reverse directions. Tandem pumps can also be used to create the equivalent flow of one larger displacement pump by combining the flows of the two pumps. This is an economic advantage over using a single large displacement pump. Tandem pumps may also be used in industrial, construction or mining applications where several sources of hydraulic power are required while taking advantage of using only one power source to drive the two pumps.
The variable displacement pump provides a flow of high pressure oil. Pump output flow can be varied to obtain the desired motor output speed. For example, when the pump’s displacement is zero, no oil is pumped and the transmission’s motor output shaft is stopped. Conversely, maximum pump displacement produces maximum motor shaft speed. The direction of high pressure flow can also be reversed; doing so reverses the direction the motor output shaft rotates. A charge pump is integrated into the piston pump and driven by the shaft of the piston pump. The drawing illustrates a suction filtration circuit. Eaton recommends a suction filter without a bypass valve. The charge pump has a Low Pressure Relief Valve.
Performance – Charge Pump
Eaton offers a choice of four charge pump displacements to go with their heavy duty transmission. These charge pumps are available with one or more of the following options:  a pressure sensing port, remote pressure side filter ports; a spin-on pressure side filter; mounting flanges for auxiliary pump. An internal charge relief valve regulates charge pressure. Charge pressure supplies the control with pressure to operate the swash plate and to maintain a minimum pressure in the low side of the transmission loop.
The charge pressure setting is referenced to case pressure. Charge pressure is the differential pressure above case pressure.
Minimum charge pressure is the lowest pressure allowed to maintain a safe working condition in the low side of the loop. Minimum control pressure requirements are a function of speed, pressure, and swash plate angle, and may be higher than the minimum charge pressure shown in the Operating parameters tables. Maximum charge pressure is the highest charge pressure allowed by the charge relief adjustment, and which provides normal component life. Elevated charge pressure can be used as a secondary means to reduce the swash plate response time. At normal operating temperature charge inlet pressure must not fall below rated charge inlet pressure (vacuum). Minimum charge inlet pressure is only allowed at cold start conditions. In some applications it is recommended to warm up the fluid (e.g. in the tank) before starting the engine and then run the engine at limited speed. Maximum charge pump inlet pressure may be applied continuously.   
Temperature and Viscosity   
Temperature: The high temperature limits apply at the hottest point in the transmission, which is normally the motor case drain. The system should generally be run at or below the quoted rated temperature.
The maximum intermittent temperature is based on material properties and should never be exceeded.
Cold oil will generally not affect the durability of the transmission components, but it may affect the ability of oil to flow and transmit power; therefore temperatures should remain 16 °C [30 °F] above the pour point of the hydraulic fluid. The minimum temperature relates to the physical properties of component materials. Size heat exchangers to keep the fluid within these limits. Viscosity: For maximum efficiency and bearing life, ensure the fluid viscosity remains in the recommended range.
The minimum viscosity should be encountered only during brief occasions of maximum ambient temperature and severe duty cycle operation. The maximum viscosity should be encountered only at cold start.  
Filtration System  
To prevent premature wear, ensure only clean fluid enters the hydrostatic transmission circuit. A filter capable of controlling the fluid cleanliness to ISO 4406 class 22/18/13 
(SAE J1165) or better, under normal operating conditions, is recommended. These cleanliness levels cannot be applied for hydraulic fluid residing in the component housing/case or any other cavity after transport. The filter may be located on the pump (integral) or in another location (remote). The integral filter has a filter bypass sensor to signal the machine operator when the filter requires changing. Filtration strategies include suction or pressure filtration. The selection of a filter depends on a number of factors including the contaminant ingression rate, the generation of contaminants in the system, the required fluid cleanliness, and the desired maintenance interval. Filters are selected to meet the above requirements using rating parameters of efficiency and capacity. Filter efficiency can be measured with a Beta ratio¹ (βX). For simple suction-filtered closed circuit transmissions and open circuit transmissions with return line filtration, a filter with a β-ratio within the range of β35-45 = 75 (β10 ≥ 2) or better has been found to be satisfactory. For some open circuit systems, and closed circuits with cylinders being supplied from the same reservoir, considerably higher filter efficiency is recommended. This also applies to systems with gears or clutches using a common reservoir. For these systems, a charge pressure or return filtration system with a filter β-ratio in the range of β15-20 = 75 (β10 ≥ 10) or better is typically required.  
Control Options – Pump Electronic Proportional Displacement Control with Swashplate Mechanical Feedback
The Electronic Proportional displacement control is ideal for applications requiring electronic pump displacement control. The EP displacement control has been designed to withstand the rigors of off-highway equipment environmental conditions.  
PumpElectronic ProportionalDisplacement Control withSwashplate Mechanical andElectronic Sensor Feedback
The Electronic Proportional displacement control with both swash plate mechanical and electronic sensor feedback is ideal for applications requiring both precise electronic pump displacement control and inherently safe operation. The dual feedback enables safety integrity level (SIL) compliance.
Standard Control with Neutral Lock-out
The neutral lock-out feature is an electrical switch that is closed when the transmission is in neutral. This switch can be used to prevent the activation of certain functions that require the pump to be in neutral. The lock-out feature is commonly used to prevent starting the prime mover or activating auxiliary functions. The electrical switch is available as normally open or normally closed.  
Remote Pressure override
The remote pressure override control provides a means to remotely adjust the pressure setting of the pressure override valve.
This control may be used in applications requiring variable system pressure protection to prevent overloads and excessive heat generation. This valve operates similarly to the IPOR control.
De-stroke Control
The heavy duty De-stroke Control is a solenoid valve mounted on the standard variable pump control.
When energized, the valve cross-ports control pressure allowing centering springs to bring the pump out of stroke. It can be energized with a single switch, push button, or dead man’s switch. The solenoid coils are available in 12 volt or 24 volt DC and normally open and normally closed configurations. 
Component Descriptions
A typical heavy duty hydrostatic transmission. The axial piston pump and axial piston motor are the main components. The filter, reservoir, heat exchanger, and oil lines make up the rest of the system. The function of each of these components is described: A separate energy source, such as an electric motor or internal combustion engine, turns the input shaft of the pump.  
Variable Displacement Axial Piston Pump
The variable displacement pump provides a flow of high pressure oil. Pump output flow can be varied to obtain the desired motor output speed. For example, when the pump’s displacement is zero, no oil is pumped and the transmission’s motor output shaft is stopped. Conversely, maximum pump displacement produces maximum motor shaft speed. The direction of high pressure flow can also be reversed; doing so reverses the direction the motor output shaft rotates.
A charge pump is integrated into the piston pump and driven by the shaft of the piston pump. The drawing illustrates a suction filtration circuit. Eaton recommends a suction filter without a bypass valve. The charge pump has a Low Pressure Relief Valve that regulates the output pressure. Power limiter valves and high pressure relief valves are available as options.
Fixed Displacement
Axial Piston Motor The motor uses the high pressure oil flow from the pump to produce transmission output. The high pressure oil comes to the motor through one of the high pressure lines. It enters the motor, turns the output shaft, and then returns to the pump. Eaton piston motor integrates a hot oil shuttle and low pressure relief valve into the end cover. The shuttle valve and low pressure relief valve direct excess charge pump flow into the motor case. The shuttle valve is activated by high pressure and directs excess charge pump flow over the low pressure relief valve. This flushing action allows the charge pump to provide clean, cool oil to the closed loop circuit.  

Eaton HHD motor Technical Data  
Table of values (theoretical values)   

Eaton HHD motor		Eaton 3933	Eaton 4633	Eaton 5433	Eaton 6433	Eaton 7630
Displacement	in3/rev	3.89	4.6	5.44	6.44	7.62
	cm3/rev	63,7	75,3	89,1	105,5	124,8
Nominal Pressure	psi	6000	6000	6000	6000	6000
	(bar)	(420)	(420)	(420)	(420)	(420)
Peak Pressure	psi	7000	7000	7000	7000	7000
	(bar)	(480)	(480)	(480)	(480)	(480)
Maximum	rpm @ 18°	4160	4160	3720	3720	2775
Shaft Speed	rpm @ 10°	5380˜	5380˜	4810˜	4810˜	3425˜
Maximum	lb-in	3511	4149	4916	5807	6911
Output Torque	Nm	397	469	556	656	781

The motor uses the high pressure oil flow from the pump to produce transmission output. The high pressure oil comes to the motor through one of the high pressure lines. It enters the motor, turns the output shaft, and then returns to the pump. Eaton piston motors integrate a hot oil shuttle and low pressure relief valve into the end cover. The shuttle valve and low pressure relief valve direct excess charge pump flow into the motor case. The shuttle valve is activated by high pressure and directs excess charge pump flow over the low pressure relief valve. This flushing action allows the charge pump to provide clean, cool oil to the closed loop circuit.  

Eaton pump part number						Eaton motor part number
3923-002	5423-367	4623-231	6423-081	4623-002	7620-094	3933-001	5433-080	4633-047	4633-190
3923-003	5423-402	4623-294	6423-279	4623-003	7620-316	3933-002	5433-087	4633-111	6433-002
3923-200	5423-417	4623-396	6423-338	4623-115	7640-032	3933-092	5433-116	4633-132	6433-009
3923-210	5423-493	4623-432	6423-449	5423-295	7620-039	3933-095	5433-138	4633-139	6433-011
3923-282	5423-518	4623-472	6423-511	6423-034	5423-004	4633-002	5433-142	4633-143	6433-042
3923-295	5423-715	4623-503	7620-000	6423-071	7620-058	4633-010	5433-203	4633-153	6433-107
3923-303	5423-867	4623-524	7620-001	6423-073	5423-016	4633-029	5433-205	5433-005	6433-120
3923-352	5423-889	4623-552	7620-010	7620-371	5423-003	4633-036	5433-216	5433-008	6433-154
3923-355	6423-005	4623-553	7620-011	4623-654	7620-037	4633-045	4633-164	7630-014	6433-187
3923-371	6423-020	4623-608