To lower the mast:
- lift the swivel with the kelly bar and fasten them on the mast;
- check the security of fixation and release the drawworks brakes (connect drill line end of the second drum to the mast);
- release the screw of clamp fastening the mast legs to the rig frame then open buckle covers;
- unlatch the clamp fastening the mast to the front legs;
- remove all things that may hinder mast lowering;
- set all the levers in the neutral position except lever No.19 which should be switched on for the drawworks;
- release levers No.4 and 5 of drawworks brakes;
- fully open the valves; the rest two valves must be closed;
- check the oil level in the hydraulic system tank; if necessary add oil up to the lower mark of the probe;
- disconnect the engine friction control cable from the pedal;
- screw up the jacks installed in the mast legs so that the thrust bearing don’t hinder mast overturning;
- actuate the engine and oil pump; slowly closing the valve No.10 increase the pressure to 1,5-2,0 mPa and maintaining it for 2-3 minutes check condition of the hydraulic system. When the troubleshooting is performed check the hydraulic system under pressure;
- then open valves No.13, 14 and close valves No.10, 11. When closing valve No.14 increase the pressure to 1,0-1,5 mPa and check condition of cylinder cups and the pipe line of the upper cylinder part.
If there is no oil leakage make 1-1,5 turns of valve No.10 to unscrew it then screw up valve No.14; it will increase pressure in the hydraulic system till the mast begins to deflect from the vertical position.
If the mast doesn’t move when the pressure is increased and the safety valve is actuated, stop the work, find out the reason of malfunction and debug it.
As the angle of lean increases the mast lowering speed also increases; it can
be decreased till safe limit by means of valve No.10 screwing up. If valve No.10
is fully closed the mast will stop in any position.
When the angle of mast lean is less than 45% open the valve 1,5-2 turns and the mast will continue to lower under its weight.
Lay the mast onto the front stake slowly to avoid damages.
When the mast is lowered switch the vehicle gearbox to idle run by toggle switch No.1 (Drawing 19) then switch off the power takeoff for the drilling rig. Afterwards turn off the mast raising pump and firmly screw up all the dispenser valves.
Fix the mast to the front leg by clamp, pressure hose – to the mast. Fix control cable of engine friction so that it will not prevent to actuate the vehicle clutch.
Close the needle valve of pneumatic system receiver. To raise the mast at slight angle (for cab tilting) close all hydraulic system valves and inject the oil to the lower room of the hydraulic jack by pendulum-type moving the handle of manual pump. The mast position is fixated with the telescopic bar set in the front leg. To lower the mast open the valve No.10.