GLASS (Front) 5K9653 - Caterpillar

Reverse combination valve (6), direction control valve (7), and reverse pressure tap (8) are located on the rear face of propel pump (1). Direction control valve (7) contains forward solenoid (11) and reverse solenoid (10). The K726-BU wire is connected to the forward solenoid, and the K725-GN wire is connected to the reverse solenoid. The machine electronic control module controls these solenoids.The strength and destination of the output signals are determined by the signals the ECM receives from the input devices (for additional information, refer to "Systems Operation"). The ECM provides a variable signal to the propel pump solenoids. Signals from the ECM with strengths between 400 and 1200 mA cause the solenoids to react. Solenoid reactions move the displacement control spool in the pump to control the flow of charge oil which acts against either side of the servo cylinder. The position of the servo cylinder controls the position of the swashplate in the pump.Propel pump (1) is equipped with flushing valve block (9). The flushing valve block contains the flushing spool, an orifice, and the flushing relief valve. The flushing relief valve is set to open at a lower pressure than the setting of charge relief valve (2) in the propel pump. Therefore, during normal operating conditions the flushing relief valve opens when the propel pump is producing flow. This results in oil being flushed from the hydrostatic circuit. The orifice in the flushing valve block controls the flow rate. The oil is flushed through the cases of the vibratory motors. Note: The orifice in the flushing valve block only allows a small amount of oil from the low pressure loop to flow into the cases of the vibratory motors compared to the total amount of charge flow available. Therefore, even though the flushing relief valve opens at a pressure lower than charge pressure, because of the orifice, charge pressure only drops slightly when the machine is moving.
Illustration 3 g01937285
Pump Cross Section "Neutral" (1) Feedback linkage (2) Orifice (3) Directional control valve (4) POR valve (5) Port plate (6) Barrel assembly (7) Piston (8) Slipper pads (9) Swashplate (10) Input shaft (11) Servo piston (12) Orifice (13) Towing bypass stud (14) Small spring (15) Combination valve (16) Large spring (17) Spindle (18) Poppet (19) Charge relief valve (20) Combination valve (21) Spool (22) Piston (23) Shuttle valve (24) Feedback linkage (25) Proportional solenoid (26) Centering spring (27) Directional control spool (28) Proportional solenoid (29) Servo pistonEngine rotation turns the pump input shaft. The input shaft is splinned to the rotating group. The rotating group contains a piston and barrel assembly. The pistons in the group rotate with the barrel assembly. The piston slipper pads allow the pistons to follow the angle of the swashplate. The rotating group only generates flow when the swashplate is not at zero angle.When the propel lever is in the NEUTRAL position, both sides of the servo piston are open to the pump case. The servo piston springs center the servo piston, and