The hydraulic system includes pump No.8 (Drawing 10) installed on the gearbox, dispenser (1), oil tank (4), hydraulic jack (5) and oil conduits. From the tank oil moves along conduit (9), sucked in the pump (8) and gets into dispenser (1) via conduit (7).
The oil in the dispenser with four valves (10, 11, 13, 14) may be guided either to the jack bottom (to raise the derrick) via conduit No.2, or to the jack top (to lower the derrick) via conduit No.6 or to the oil tank via conduit No.3.
The dispenser consists of the case fastened to the bracket by bolts. On the right side the case is equipped with valves No.10 and 11; on the left side – valves No. 13 and 14.
The hydraulic system has manual oil pump (15); its function is to raise the derrick at slight angle so that to throw back the cab if the engine has broke down.
From pump the oil gets into the connecting branch (back valve with spring (12) move the ball aside) and then to the connecting channel. Shutoff valves (11 and 13) close cross channels that lead to the connecting branches of raising conduits and to the top of hydraulic jack. Cross channels have orifices with valves (10 and 14); rooms of these valves are interconnected by common link incoming to the connecting branch of the unloading line. Over connecting channel there is a safety valve consisting of ball with spring; one end of the spring is inserted into the cage, the other one leans on the ball via guide through special plate. When the safety valve is active oil raises the ball and gets into the low drain channel through horizontal and vertical orifices. The drain channel is under the rooms of valves No. 10 and 14.
Drawing 10. Jack Hydraulic System:
1 - dispenser; 2, 6, 7, 9 - conduits; 3 - unloading line; 4 - oil tank; 5
– hydraulic jack; 8 - pump; 10, 11, 13, 14 - valves; 12 - spring; 15 – manual
a – oil motion when lowering the mast; b - oil motion when raising the mast; c – from pump to dispenser; d - to drain
All sealings between dispenser case, connecting branches and valves are copper gaskets; the gasket of valve spindle is made of oil resistant rubber.
Double-step hydraulic jack (for raising and lowering the mast) consists of the following parts (Drawing 11): jacking pad (1), outer cylinder (4), inner piston (7). The pistons are sealed by cups (11 and 12).
Drawing 11. Hydraulic Jack.
1 - jacking pad; 2 - bearing; 3 – connecting branch; 4 - cylinder; 5 -
piston; 6 - inner cylinder; 7 - piston: 8 - roller; 9 - eye; 10 - fork; 11, 12 -
cups; 13 - valve; 14 - connecting branch
The jacking pad is mounted on the bearings (2). The rod is connected with the mast through the fork (10), roller (8) and eye (9). The sealing between cylinder bottom and the jacking pad is copper. To raise the mast the oil is supplied to the lower room through the connecting branch (14); to lower the mast – to the upper room through the connecting branch (3). To prevent oil leakage the copper gaskets are inserted in the pivot recesses; the gaskets are compressed by connecting branches when screwing. In the jacking pad (1) there is a valve (13) which decreases the oil flow to the front pad when the derrick is being lowered. Oil is supplied to the upper and lower cylinder rooms through the oil devices mounted in the pad (1) pivot. To prevent oil leakage the copper gaskets are inserted in the pivot recesses; the gaskets are compressed by connecting branches (3 and 14) when screwing. Threaded head of the jacking pad is equipped with the valve which serves as the safety device when lowering the mast.
Drawing 12. Hydraulic Circuit Diagram:
1 – oil tank; 2 – manual pump; 3 - pump; 4 - manometer; 5 - hydraulic jack; 6 – dispenser