PLATE-LOCK 1923324 - Caterpillar

Illustration 1 g02741162
Main Control Valves
(1) Plug (bucket shock reducing valve)
(2) Plug (travel shock reducing valve)
(3) Plug (stick shock reducing valve)
(4) Plug (stabilizer/dozer shock reducing valve)
(5) Plug (Boom shock reducing valve)
(6) Plug (VA boom shock reducing valve)
Illustration 2 g02741163
Typical Main Control Valve Schematic (Bucket Circuit)
( 7) Bucket Cylinder
(8) Diverter Ball Valves
(9) Reducing Valve (Shock)
(10) Bucket Valve in Main Control Valve
(11) Load Sensing Circuit
(12) Right-hand Joystick Circuit
(13) Pilot Pump
(14) Engine
(15) Implement Pump
(16) Line Relief Valves
(17) Tank
(18) Control Valve (Bucket)
(19) Work Tool Attachment
Illustration 3 g02807998
Shock Reducing Valve
(A) OPEN position
(B) CLOSED position
(9) Reducing Valve (Shock)
(10) Bucket Valve in Main Control Valve
(20) Orifice check valve
(21) Passage to pilot control valve
(22) Passage to control Valve
(23) Control valve spool The shock reducing valves are located in the main control valve in the pilot line supply passage for the following positions: boom raise, boom lower, bucket close, bucket open, forward travel, stick in, stick out, blade/stabilizer up, blade/stabilizer down, VA boom raise and VA boom lower.When the pilot control valve lever is moved and the orifice check valve (20) moves to OPEN position (A), pilot oil is sent from the pilot control valve to passage (21) of the shock reducing valve. Pilot pressure acts against the surface of orifice check valve (20) in order to unseat the valve. This operation will permit oil flow to control valve spool (23) through passage (22). Full pilot oil is now allowed to flow to the main control valve to move the control valve spool (23). When the pilot control valve is placed in the NEUTRAL position, the pilot oil is restricted from returning to the hydraulic tank by orifice check valve (20) moving to CLOSED position (B). Closed orifice check valve (20) reduces the speed of control valve spool (23) as the spool returns to the center position. Slowing the flow of the pilot oil causes the hydraulic control valve spool (23) to return to neutral gradually in order to help to reduce shock loads at the end of the spool travel. Both shock reducing valves operate the same way dependent upon travel of control valve spool (23).