COUPLING AS- 3236233 - Caterpillar

Illustration 10 g06058161
Screed Lift Hydraulic Circuit - HALT
(1) Screed-assist pressure sensor
(2) Auxiliary manifold
(3) Screed raise valve
(4) Screed lower valve
(5) Screed-assist valve
(6) Relief valve
(7) Screed power lift valve
(8) Screed lock valves
(9) Screed lift cylindersThe schematic shown above illustrates the screed hydraulic circuit operated under the following conditions:
Machine is stopped
Halt is selectedIn this condition, screed-assist valve (5) and screed lower valve (4) shift. This action directs oil to the head end of screed lift cylinders (9).When HALT mode is active, the reference pressure for screed-assist valve (5) is return line pressure. The screed-assist valve is also opened proportionally in the HALT mode. This combined action limits the cylinder pressure between 0-6000 kPa (870 psi). In this case, the circuit maintains a given force against screed lock valves (8) and holds the screed in place.Note: The initial pressure is set to 3000 kPa (435 psi). The machine ECM and transmission ECM monitor and maintain the selected pressure.Pump supply oil flows across screed lower valve (4) and is directed out of auxiliary manifold (2) through port"SCD3". In this case, oil flows to the head end of screed lift cylinders (9). As oil fills the head end of the cylinders, the rods in the cylinders begin to extend. A check valve in screed lock valves (8) prevents oil from leaving the rod end of the cylinders. The oil in the rod end of the cylinders is trapped. Increased pressure causes the cylinders to apply a preset downward force on the screed.Tow Point Control Circuit
Illustration 11 g06057156
Tow Point Hydraulic Circuit - RAISE
(1) Left tow point cylinder
(2) Counterbalance valve
(3) Left hopper and tow point manifold
(4) To left hopper control circuit
(5) Right tow point cylinder
(6) Counterbalance valve
(7) Right hopper and tow point manifold
(8) To right hopper control circuit 9 Left tow point control valve
(10) From port"Y" steering manifold
(11) Right tow point control valve
(12) To apron fold valve and truck hitch valves
(13) To port"F" return manifoldWhen the left tow point raise function is active, the left tow point raise solenoid is energized. Pump supply oil flows across tow point control valve (9) and is directed to counterbalance valves (2). The counterbalance valves consist of two check valves and two spools.Oil flows through the right check valve of counterbalance valves (2) and exits the left hopper and tow point manifold (3) through port"C1". Oil enters the rod end of left tow point cylinder (1), and the cylinder begins to retract.Displaced oil from the head end of the cylinder is directed back to the left hopper and tow point manifold (3) through port"C2". The displaced oil flows to the return side of counterbalance valves (2).Initially, the counterbalance valve blocks the return oil. As pressure increases, the spool in the line to the head end of left tow point cylinder (1) shifts. In this case, oil is directed across tow point control valve (9) and out port"T" of left hopper and tow point manifold (3).Note: The right tow point system follows the same principles of operation as the left. The tow point