CRANKSHAFT GP 1853190 - Caterpillar

Dump Trucks With Restrictor/Check Valve In The Nitrogen Suspension SystemsIf the restrictor/check valve(s) in the oil nitrogen suspension system(s) is blocked, the suspension cannot be lowered by the normal method for servicing purposes.
Three-axle machines and two-axle machines without rear suspensions have one restrictor/check valve. Two-axle machines with rear suspensions have two restrictor/check valves, one for the front and one for the rear suspension system.
The purpose of the restrictor/check valve is to allow free flow of oil into the suspension cylinders to raise the ride height, while restricting the flow of oil out of the cylinders to control the speed at which the suspension lowers.
The following procedure must be used to lower the suspension system to the service position if a restrictor/check valve becomes blocked.
1. Park the machine on level ground. Disengage the inter axle differential lock or four wheel drive and stop the engine.2. Block the trailer wheels if lowering the front suspension, or the tractor wheels if lowering the rear suspension and disengage the parking brakes.3. Carefully release all nitrogen gas pressure from the suspension accumulator(s) by opening the charging valve(s) slightly. For front suspension systems, only one accumulator is used. Rear suspension systems have two.4. Lift the front or rear of the machine and support on suitable stands with the wheels just above the ground. This and the absence of gas pressure in the accumulator(s) should ensure there is no residual pressure locked in the circuit which connects the restrictor/check valve to the cylinders and accumulator(s).5. The hydraulic line connecting the restrictor/check valve to the cylinders and accumulator can now be carefully removed.6. Remove and service or replace the restrictor/check valve.7. Install the serviced or new restrictor/check valve.8. Install the hydraulic line connecting the valve to the cylinders.9. Lower the machine to the ground.10. Charge the suspension accumulator(s) as described in the Service Manual.