D6 Track-Type Tractor Systems Caterpillar

Piston Motor (Steering)

Usage:

D6 AG9

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Illustration 1	g06258200
(1) Barrel (2) Pivot pin (3) Pistons (4) Retaining plate (5) Case (6) Shaft (7) Port plate (8) Head

The steering motor is a fixed displacement bent axis motor with a self-contained flushing valve. The flushing valve is located in port plate (7). The motor is operated by pressure oil from the variable displacement piston pump.

Oil flow through the motor can be in either direction. A change to the direction of the oil flow changes the direction of rotation of barrel (1), pistons (3), and shaft (6). A change in the direction of the oil flow through the motor does not change the amount of output torque from the shaft of the motor.

The components of the motor that turns are the following components: shaft (6), retaining plate (4), pistons, (3) and barrel (1). The parts that do not turn are the following parts: head (8), case, (5) and port plate (7).

Oil from the pump flows to the steering motor. The oil flows through the inlet port in head (8) to the inlet control slot of port plate (7). The direction of the flow from the motor determines the inlet and the outlet in port plate (7) and in head (8). Oil through port plate (7) flows into the cylinders of barrel (1) that are over the inlet control slot of port plate (7).

The spherical heads of pistons (3) are held by retaining plate (4). The heads are held in sockets in shaft (6). The ends of pistons (3) are positioned in barrel (1). Barrel (1) rotates about pivot pin (2). Because of the arrangement between the pistons and the shaft, pistons (3) move in and out of the barrel. This movement occurs as the pressure oil enters the cylinders and as the oil leaves the cylinders. The pressure oil from the inlet control slot forces the pistons out of the barrel. This causes shaft (6) and barrel (1) to rotate.

As shaft (6), pistons (3) and barrel (1) rotate, the pistons reach the top center position (fully extended position). At the same time, the cylinder begins to overlap the outlet control slot in port plate (7). Now, the piston starts to move back into the barrel. By moving into the barrel, the pistons push oil out of the cylinder into the outlet control slot in port plate (7). The oil flows through the outlet port in head (8) to the pump. The ball (head) of center pin (2) is the pivot point for barrel (1).

The flushing valve is located in port plate (7). The flushing valve allows oil from the steering motor to flow into case (5). The oil cools the components of the motor. Also, the oil lubricates the components of the motor, and the oil flushes the components of the motor.

The pressure oil in either control slot will move the rod . Slots in the rod allow low-pressure return oil to flow into the passage. A drilled passage in pivot pin (2) allows the oil to flow to the pivot pin socket and on through passages to the motor bearings. The flushing oil from the motor case then combines with the steering pump case drain and flows to the case drain filter and to the hydraulic tank.

The flushing valve only allows oil flow when the machine is in a turning condition and pressure oil is available to the rod.