H35D S, H45D S, H55D S and H65D S Hydraulic Hammers Caterpillar

Color Code for Schematics

Illustration 1	g01296908

Feature Identification

Illustration 2	g01296919
(1) Spool (pressure adjusting valve) (2) Low pressure accumulator (3) Pilot passage (4) Piston groove (5) Shoulder of piston (6) Piston (7) Distributor (high pressure side) (8) Distributor (9) Top of piston (10) Distributor (low pressure side) (11) Shoulder of piston (low pressure)

Start Cycle

Illustration 3	g01296936
Start cycle

• The start cycle begins with the distributor (8) and piston (9) in a neutral position.

• The pressure control valve (1) is in a closed position due to spring force. In this position, the incoming oil charges the low pressure circuit.

• When the pressure increases, the spool (1) shifts. When the spool shifts, oil causes the piston to lift.

Lift Cycle

Illustration 4	g01296946
Lifting cycle

• The pressure adjusting valve directs oil to the distributor (7).

• The high pressure oil is directed to the piston (6), and to pilot passage (3). The oil is also directed to the distributor's pilot shoulder (10). The distributor moves upward.

• The piston moves upward due to high oil pressure on the lifting diameter of piston (5). When the piston moves upward, oil from the top shoulder of the piston (11) travels to the low pressure accumulator. The pressure increases in preparation for the firing cycle.

• Oil at the top diameter of the piston (9) is discharged to the tank.

Firing Cycle

Illustration 5	g01296978
Firing cycle

• As the piston raises, the piston's shoulder (5) opens to the pilot passage (3). This provides low pressure oil to the shoulder of the distributor (10).

• The distributor moves down due to the pressure differential. High pressure oil is directed to the top of the piston (9). The shoulder of the piston (11) moves downward. The oil that is stored by the low pressure accumulator acts on the piston. A net downward force is created on the piston.

Return Cycle

Illustration 6	g01297073
Return cycle

• As the piston strikes the tool, the pilot chamber (5) is opened to high pressure oil. The distributor (8) is opened to high pressure oil. This causes the distributor (8) to move upward.

• The oil from the top of the piston (9) is directed to the tank. The operation cycle continues.