Usage:
426C (1CR, 1MR) 436C (1FR, 1PR) 438C (1TR, 2DR) Backhoe Loaders
The C-Series All-Wheel-Steer models use a different brake actuation system than the C-Series Two-Wheel-Steer model. The Two-Wheel-Steer models use a self contained brake system which is composed of a master brake cylinder/valve, reservoir, and associated lines connected directly to the rear axle brakes.
Illustration 1. 136-5942 Brake Control Valve Group (1).
Illustration 2. Location of 148-9000 Valve Assembly (2).
The All-Wheel-Steer models employ a limited slip axle which uses a hydraulic assisted brake system controlled by a single pedal. The All-Wheel-Steer machines derive brake actuation oil from the steering circuit of the machine's hydraulic system. The brake system is composed of 136-5942 Brake Control Valve Group (1) (Illustration 1), 148-9000 Valve Assembly and associated lines that connect the brake system to hydraulic system and the All-Wheel-Steer Brakes.
Illustration 3. Hydraulic Schematic.
The 136-5942 Hydraulic Brake Control valve provides a signal to the hydraulic pump and controls flow and pressure to the rear axle brakes.
The 148-9000 Brake Sequence Valve prevents interaction between the brakes and other portions of the hydraulic system. Maximum Brake System pressure is controlled by the relief valve in the Steering Priority Valve Pressures can be measured at the pressure taps provided on the pump. See Chart 2 for typical pressures expected when the brakes are operating properly. These pressures are measured when the engine is running and the brakes are fully applied.
Procedure To Test Brakes
1. Back the machine up an incline which is between 15% and 20%.
2. Set parking brake to hold the machine.
3. Shut off engine.
4. Using high force, approximately 668 N (150 lb), depress the brake pedal.
5. Release parking brake.
6. The machine should not move after increasing pedal force to 668 N (150 lb).
7. If the machine moves, the brake control valve is not functioning correctly and should be replaced.