SPECIFICATIONS

Vehicle Systems Systems Operation

Oil Flow

The oil from the priority valve flows through inlet (4).

When the steering wheel is stationary (NEUTRAL),

the oil is stopped by spool (1). The oil can not flow

through the steering gear to the steering cylinder

until the steering wheel is turned.

The steering wheel is connected to spool (1) by a

shaft assembly and splines. When the steering wheel

is turned, spool (1) turns a small amount until springs

(7) are compressed. Then, sleeve (2) starts to turn.

As long as the steering wheel is turned, the spool

and sleeve both turn as a unit, but they turn a few

degrees apart.

When the spool and sleeve are a few degrees apart,

oil passages are opened between them. This lets the

pump oil from inlet (4) flow through passages in body

(11) to the metering section.

When the steering wheel is turned, pin (8) turns with

the sleeve and causes drive (12) to turn also. The

drive causes a rotation of gear (5) inside gear (6).

This rotation of the gear sends a controlled

(metered) flow of pilot oil back through body (11).

This oil flows to port (9) or (10) and then to the steer-

ing cylinder. Port (9) or (10), that is not used for pres-

sure oil to the steering cylinder, is used for return oil

from the other end of the steering cylinder.

Pump Gears In Metering Section

(5) Internal pump gear. (6) External pump gear. (8) Pin. (12) Drive.

If the steering wheel rotation is stopped, springs (7)

will move sleeve (2) back in alignment with spool (1)

(NEUTRAL position). This will close passages

between the metering section and control section

and the steering gear will be in the NEUTRAL posi-

tion.

When the engine is off, the steering gear can be

manually operated. The control section will work as a

pump. The oil that is returned from the steering cylin-

der is not returned to the tank. The suction of the

control section will open an internal check valve and

let return oil from the steering cylinder go to the inlet

side of the control section. During power operation,

supply pressure keeps the check valve closed.

IDCS114S