Construction
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| Illustration 1 | g01179881 |
(1) Shaft (2) Swashplate (5) Retainers (4) Piston (3) Slippers (6) Barrel (7) Valve plate (8) Brake assembly (9) Friction plate (10) Brake piston (11) Spring (12) Relief valve assembly (13) Makeup valve (14) Pinion shaft (15) Planetary gear assembly | |
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| Illustration 2 | g01176048 |
General view of swing motor (16) Makeup (17) Pressure port A (18) Case drain (19) Pressure port B | |
The internal construction of the swing motor is divided into the following three groups:
- Rotary group that consists of motor shaft (1), slippers (3), pistons (4), retainer (5), barrel (6), pinion gear (14), and planetary gear assembly (15).
- The parking brake group consists of the friction plate (9), spring (11), and piston (10) .
- The combination line relief and makeup valve consists of relief valves (12) and check valves (13) .
Operation
Oil from the swing control valve enters the swing motor at pressure port (17). The motor begins to rotate shaft (1). The shaft is connected to planetary gear assembly (15). The planetary gear assembly rotates pinion shaft (14). The return oil flows out of pressure port (19) .
The reverse rotation functions in the opposite manner. The oil enters pressure port (19) and the return oil flows through pressure port (17) .
Shock Reducing Valve
The shock reducing valve consists of a direct relief valve and a piston for changing the force of the spring. Pressure port (17) and pressure port (19) are blocked when the swing operation is stopped. The swing motor attempts to turn further, due to the inertia forces of the upper structure. A brake pressure occurs in pressure port (19) of the swing motor according to the pumping action of the swing motor. This is known as a shock load.
The shock reducing valve slows down the brake pressure. Also, the shock reducing valve reduces the shock load. The shock reducing valve functions when the swing function starts and when the swing function stops.
Operation
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| Illustration 3 | g01175764 |
First stage relief valve (1) Poppet (2) Spring | |
When the pressure P1 increases, poppet (1) opens when the pressure is greater than the force from spring (2).
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| Illustration 4 | g01175766 |
Second stage relief valve (3) Throttle (4) Secondary chamber | |
If the oil pressure P1 enters secondary chamber (4) through throttle (3), the pressure will move the piston and the pressure will compress the spring. The force of the spring increases the P1 pressure until the set pressure Ps is reached. The shock load at the start of swing and swing stop is slowed down by the above operation.