KIT-OVERHAUL 5356115 - Caterpillar

Illustration 1 g00516695
Steering and Brake Control (Engine Stopped) (1) Drain (2) Clutch or brake chamber (3) Passage (4) Pressure feedback chamber (5) Supply oil chamber (6) Pilot pressure chamber (7) Spool (8) Hole (9) Passage (11) Pilot pressure chamber (12) Drain chamber (A) Parking and secondary valve solenoids (view only shows one solenoid) (B) Accumulator piston (C) Parking and secondary valves (view only shows one valve) (D) Reducing spool (E) Shut off valve (F) Pilot valve (G) Proportional solenoidThe steering and brake control valve is installed on top of the case. The control valve is operated electrically by the Electronic Control Module (ECM). The ECM responds to operator movement of the Finger Tip Control (FTC) levers.The first movement of an FTC lever modulates disengagement of the steering clutch. The machine makes a gradual turn. Further movement of the FTC lever modulates engagement of the brake and the machine makes a sharper turn. The foot brake pedal modulates engagement of both brakes and stops the machine. The parking brake switch engages both brakes and prevents the machine from moving.The steering clutches are engaged with hydraulic pressure. The brakes are engaged with spring force. Hydraulic pressure is required to disengage the brakes. If hydraulic pressure is lost, the steering clutches will disengage and the brakes will fully engage due to the spring force.The steering and brake control valve consists of a valve body and manifold which contain separate sections for each steering clutch and brake, as well as a parking and secondary brake valve body for the brake sections. For each clutch and brake, there is a pilot valve (F) operated by proportional solenoid (G), an accumulator piston (B) and a reducing spool (D). These components operate the same way for each clutch and brake to control the clutch or brake pressure. In addition, each brake control has shut off valve assembly (E) to drain brake pressure gradually if pilot valve (F) pressure drops suddenly. This is to prevent sudden brake engagement due to an electrical failure, while otherwise allowing the operator to rapidly apply brakes. The brakes also have a parking and secondary valve (C) operated by two ON OFF solenoids (A). The two brake (parking and secondary) valve solenoids (A) are connected to the parking brake switch and service brake "end of travel" switch. The solenoids are controlled by these switches in addition to the ECM. The parking and secondary valves enable the operator to apply brakes immediately, without modulation by the shut off valve.Solenoid (G), controlled by the ECM, sets the force in the pilot valve assembly (F) .Pilot valve assembly (F) regulates the pilot pressure in chamber (11), passage (9) and chamber (6). This pressure is determined by the force applied by solenoid (G). This pressure determines the pressure setting of reducing spool (D) .Reducing spool (D) regulates the flow of oil to the clutch or brake in order to maintain a pressure slightly lower than the pilot pressure in chamber (6) at the left end of