TRUNNION 4F1767 - Caterpillar

Oil flow
In the level ride position, oil from the small cartridge of the hydraulic pump enters the control valve through port (6) and flows across the spool through passages (23), (24) and (26), and out through port (9) to the hoist system. At the same time pump oil passes through load check valve (1) into passages (10), (25), (16) and (17).In the suspension raise position the spool is offset towards the solenoid end of the valve. Passages (23), (24) and (26) are closed off from outlet (9) by the spool, and passage (16) is opened. The full pump flow passes through check valve (1), along passages (10), (25), (16) and (15), round adaptor (18), and out through service port (2) to the suspension accumulator and cylinders. The pressure developed in the system is felt on the relief valve piston through passage (11) and holes (27) in the cartridge casing.In the lower position the spool is offset away from the solenoid. Passages (23), (24) and (26) remain open to outlet port (9), and passage (14) is connected to passage (15). The full pump flow passes through passages (23), (24) and (26), across the spool center, and out through port (9) to the hoist system. The weight of the truck forces oil from the accumulator and suspension cylinders through service port (2) past adaptor (18) into passage (15), tank passage (14), gallery (12), and out through tank port (5) to the hydraulic tank.Suspension Control Valve D44B
The valve used on the D44B is basically two of the valves described previously joined together. See the topic "Suspension Control Valve D550B" The two single valves are joined to form one unit with two spools and two pilot mechanisms. The pump is connected to the inlet port (5) of the front suspension valve, and a high pressure carryover adaptor (13) is fitted between outlet port (14), and the inlet port (12) of the rear suspension valve. The outlet from the rear suspension valve (8) is connected to the hoist system.The load check valve is removed from the front unit and a plug (10) is installed in its place. A plug is removed from port (15) in the front suspension valve to form a common tank gallery between the the two units.The methods of actuation (pilot mechanisms) and the resulting flows in and out of the systems are as described for the D550B.
Suspension Control Valve
(1) Port to Rear Suspension (2) Plug (3) Port to Front Suspension (4) Test Point (5) Pump Inlet (6) Relief Valve Cartridge (7) Relief Valve Cartridge (8) Outlet to Hoist Circuit
Suspension Control Valve Joining Arrangement
(9) Front Suspension Valve (10) Plug (11) Rear Suspension Valve (12) Inlet Port (13) High Pressure Carryover Adaptor (14) Outlet PortPilot mechanism
The pilot mechanism consists of two electrical solenoids (3) and (8), two air valves (4) and (7) and air cylinder (12).When the suspension is in level ride both solenoids are de-energised. Air in passages (2) and (9) is blocked at the air valves and both sides