KIT- 4861405 - Caterpillar

Illustration 1 g03342064
View of the cushion hitch pump and the pump control valve mounted on the rear of the steering pump.
Illustration 2 g03342197
Piston Pump (Cushion-Hitch)
(1) Inlet opening from the hydraulic tank
(2) Control piston
(3) Barrel
(4) Pistons (Nine)
(5) Swashplate
(6) Pump drive shaft
(7) Spring for swashplate
(8) Outlet opening to the cushion-hitch hydraulic system
(9) Pump control valve (cushion-hitch) The cushion-hitch pump is an axial piston type pump which is mounted on the transfer case at the rear of the tractor.The cushion-hitch pump has nine pistons (4). When pump drive shaft (6) turns, barrel (3), the retraction plate, and the slippers turn. The piston ends connect to the slippers. Swashplate (5) does not turn. There is a bearing journal on each side of the swashplate. The two bearing journals are inside bearings which allow movement of the swashplate. Oil flow through the passages in the pistons lubricates the internal components of the pump.When swashplate (5) is at the maximum angle and pump drive shaft (6) is turning, pistons (4) are moved in and out of barrel (3). As the pistons move out of the barrel, the pistons create a vacuum at inlet opening from the hydraulic tank (1). The hydraulic tank pressure is maintained at a sufficient level to not allow cavitation as the oil is drawn into the pump. The oil passes through the inlet opening and into the piston bore in the barrel. As the barrel continues to turn, the pistons are pushed into the barrel as the slippers rotate up the angle of swashplate (5). The pistons push the oil from the piston bore through pump the outlet opening to the cushion-hitch system.When the engine is operating, the pump will produce flow and pressure in order to satisfy the following conditions:
The demand of the cushion-hitch system
The demand for the pilot pressure for the leveling valve
The pressure setting of the pressure compensator
The internal lubrication of the pump components
The demand of the pilot pressure for the implement system
The demand of the push-pull hydraulic systemPump Control Valve
Illustration 3 g00808374
Pump Control Valve (Cushion-Hitch) (9)
( 10) Flow compensator spool
(11) Springs
(12) Setscrew
(13) Pressure compensator spool
(14) Passage from the outlet opening of the piston pump (cushion-hitch)
(15) Passage to the control piston of the piston pump (cushion-hitch)
(16) Drain passage
(17) Springs
(18) Setscrew The pump control valve is set to function only as a pressure compensator. Setscrew (12) is set so that the flow compensator does not function.The pressure compensator regulates the output flow of the cushion-hitch piston pump. The output of the pump is controlled by the angle of the swashplate.When the engine is operating and the oil pressure in the cushion-hitch hydraulic system is less than the pressure setting of the pressure compensator, the oil from the outlet opening of the piston pump flows through passage from the outlet opening of the piston pump (cushion-hitch) (14). The oil is stopped by pressure compensator spool (13) and opposing force from springs (17). There is no flow to the control piston in the piston pump and the swashplate is at the maximum angle.