320C Excavator Hydraulic System – Travel Motor



Illustration 1 g00682968

Travel motor

(1) Drive shaft

(2) Stopper

(3) Piston

(4) Swashplate

(5) Slipper

(6) Retainer

(7) Barrel

(8) Piston guide

(9) Check valve

(10) Check valve

(11) Passage

(12) Brake pilot valve

(13) Port

(14) Valve plate

(15) Head

(16) Stopper

(17) Piston

(18) Guide

(19) Spacer

(20) Spring

(21) Piston

(22) Friction plate

(23) Separator plate

(24) Passage

(25) Passage

(26) Brake spring

(27) Brake piston

(28) Port

(29) Drain port

(30) Port

(31) Port

(32) Spool

(33) Spring

(34) Displacement change valve



Illustration 2 g00766167

Travel motor (partial schematic)

(3) Piston

(4) Swashplate

(9) Check valve

(10) Check valve

(12) Brake pilot valve

(14) Valve plate

(17) Piston

(28) Port

(29) Drain port

(30) Port

(31) Port

(34) Displacement change valve

The travel motor can be divided into the following three groups:

  • The rotary group consists of the following components: drive shaft (1), slippers (5), retainer (6), barrel (7), guide (18), spacer (19), spring (20) and piston (21) .

  • The parking brake consists of the following components: piston guide (8), brake pilot valve (12), friction plates (22), separator plates (23), brake spring (26) and brake piston (27) .

  • The displacement change valve consists of the following components: piston (3), check valve (9), check valve (10), piston (17) and displacement change valve (34) .

The flow of the oil delivery from the pump depends on the direction of travel. The oil delivery from the pump flows into the travel motor through port (30) or port (31). Pump oil is forced out of the travel motor through port (31) or (30) .

The case drain oil returns to the hydraulic tank through drain port (29) of head (15) .

The oil delivery from the left pump flows into the left travel motor through port (30) during forward travel. The oil from port (30) flows through passage (11) in head (15) and through passage (25) in valve plate (14). The oil then flows through passage (24) of barrel (7) and the oil forces pistons (21) to move to the left.




Illustration 3 g00700542

Motor passage (side view from head)

(A) Top center

(B) Outlet side (low pressure)

(C) Bottom center

(D) Inlet side (high pressure)

(24) Passage (barrel)

(25) Passage (valve plate)

(35) Passage (valve plate)

Slipper (5) is coupled to the piston. Slipper (5) and the piston slide on the surface of plate (4) from the top center to the bottom center. Slipper (5) and the piston rotate with barrel (7). Left pump supply oil flows through passage (25) of valve plate (14) into pistons (21). Oil is discharged through passage (11) of piston (21). The oil then flows through passage (35) of valve plate (14). The oil then flows through port (31). The barrel turns counterclockwise.

Drive shaft (1) is splined to barrel (7). The shaft and barrel of the left travel motor rotate counterclockwise for forward travel.

In reverse travel, port (30) functions as an oil return port. Port (31) functions as a supply port. The left travel motor rotates clockwise.

When the right travel motor receives the oil delivery from the right pump through port (30), the right travel motor turns clockwise for forward travel. When the oil delivery from the right pump flows through port (31), the right travel motor turns counterclockwise for reverse travel.