COUPLING AS- 3236210 - Caterpillar

Illustration 1 g06057800
Tamper Hydraulic System OFF
(1) Displacement piston
(2) Bias spring
(3) Feedback spring
(4) Check valve
(5) Flushing control spool
(6) Pressure compensator spool
(7) Displacement control spool
(8) Tamper solenoid
(9) Tamper pump
(10) From hydraulic tank
(11) Displacement piston cavity
(12) To hydraulic tank
(13) To hydraulic tank
(14) To return filter
(15) Screed tamper motorsWhen the engine is not operating, bias spring (2) forces the swashplate in tamper pump (9) to maximum angle. When the engine is started, the pump begins to produce flow. Supply oil is sent to displacement control spool (7), pressure compensator spool (6), and to flushing control spool (5) located inside the pump. Supply oil is also sent out port"B" of the pump.When the tamper is OFF, tamper solenoid (8) is not energized. In this situation, supply oil flows across displacement control spool (7) and divides into two branches. One branch directs oil into displacement piston cavity (11). The other branch directs oil to the end of the displacement control spool.As the pressure in displacement piston cavity (11) increases, displacement piston (1) moves the swashplate toward the minimum angle. At the same time, the pressure at the end of displacement control spool (7) causes the spool to shift. In this case, a passage for supply oil opens allowing some oil to flow across the displacement control spool and into the pump case.This flow causes pressure in displacement piston cavity (11) to decrease. In this case, bias spring (2) causes displacement piston (1) to increase the angle of the swashplate. Movement of the displacement piston causes feedback spring (3) to exert a greater force against displacement control spool (7). The case drain passage in the control spool closes, and more supply oil is forced into the displacement piston cavity. Eventually, the pump reaches equilibrium, and the pump produces enough flow to make up for system leakage. In this case, the pump does not produce enough flow to overcome the restriction of the tamper motors, and the motors do not operate.When the tamper is not operating, force from the spring that acts on flushing control spool (5) is greater than pump supply pressure force. In this case, the flushing control spool allows some supply oil to flow into the pump case to cool the pump.
Illustration 2 g06057813
Tamper Hydraulic System ON
(1) Displacement piston
(2) Bias spring
(3) Feedback spring
(4) Check valve
(5) Flushing control spool
(6) Pressure compensator spool
(7) Displacement control spool
(8) Tamper solenoid
(9) Tamper pump
(10) From hydraulic tank
(11) Displacement piston cavity
(12) To hydraulic tank
(13) To hydraulic tank
(14) To return filter
(15) Screed tamper motorsWhen the tamper system is operating, tamper solenoid (8) is energized. The tamper solenoid moves displacement control spool (7) into a position that is proportional to the input signal to the tamper solenoid.Tamper solenoid (8) uses displacement control spool (7) to control the oil pressure in displacement piston cavity (11). When the input signal to the tamper solenoid increases, the pressure in the displacement piston cavity decreases. Therefore, a greater input signal results in a greater swashplate angle, and greater flow from the pump.When the pump supply pressure exceeds the