14H and 16H Motor Graders Hydraulic and Steering System Caterpillar

Illustration 1	g00931639
(1) Cross passage for left turn (2) Left relief valve (3) Right relief valve (4) Cross passage for right turn

The steering cylinder crossover relief valve is used to prevent damage from high pressure oil in the steering cylinder circuit.

If a front wheel would strike against a large object that cannot move, the pressure of the oil increases in one end of each steering cylinder. Also, the pressure of the oil increases in the oil lines. The increase in oil pressure is sensed in either passage (1) or (4). If the oil pressure increases to approximately 22100 kPa (3200 psi), the relief valve (2) or (3) will open. Either the oil will flow to the head end of the steering cylinders, or the rod end of the steering cylinders.