Metering Pump (Steering)
SMCS Code: 4312
Part No.: 1G-9787
(1) Inner Spool. (2) Sleeve. (3) Outlet port. (4) Load sensing
line port. (5) Inlet port. (6) Rotor. (7) Rotor ring. (8) Drive
shaft. (9) Centering springs. (10) Pin. (11) Internal check
valve. (12) Left turn port. (12) Right tun port. (13) Housing.
The metering pump is made up of the following two sections:
Control section (A)
Metering section (B)
The two sections are connected by hydraulics and by
mechanics. The two sections work together in order to send oil
to the steering cylinders.
Pump oil goes through inlet port (5) into control section (A).
When the steering wheel is turned, control section (A) sends oil
to metering section (B). Metering section (B) produces a
specific amount of oil flow. Metered oil from metering section
(B) is then directed by control section (A) to either left turn port
11 or right turn port (13).
Metering section (B) is a small hydraulic pump. The hydraulic
pump produces a metered amount of oil flow. Then, the
metered oil is directed by the control section (A) to the steering
The direction and the speed are controlled by the metering
pump. As the steering wheel is turned faster, there is an
increase in the flow of oil from the metering pump to the
cylinders. The increased flow causes the cylinders to move
faster. The result is faster movement of the machine.
Oil flows through outlet port (3). When the steering wheel is in
the NO STEER position, the oil is stopped by spool (1). The oil
cannot flow to the metering pump to the steering cylinders until
the steering wheel is turned.
The steering column is connected to the spool (1) by a shaft
and a spline coupling.
When the steering wheel is turned, spool (1) turns a small
amount until springs (9) are compressed. When the drive
pinion contacts the ends of the slots, the sleeve (2) also turns.
While the steering wheel is turning, the spool and the sleeve
are spread apart by a few degrees. The spool and the sleeve
rotate as one unit. The centering springs are compressed.
The initial movement of the spool opens the oil passages
between the control section and the metering section. This
allows the oil flow from inlet pod (5) to go to the metering