Feed unit receives rotation from transmission via worm reduction gearbox No.1 (Drawing 9). From this worm reduction gearbox the rotation is transmitted through the tooth-type half-clutch (2) and sprocket (3) to the sprockets of feed unit chain drive.
The drilling rig has a cable-chain mechanism for forced tool feeding. The
crown block of mast has four rollers; two extreme rollers hold feed unit cables,
two middle rollers – cables of drawworks drum. Cables ends are fixed to cheeks
on swivel pivot on the one side, on the other side – to draw bars.
Single-strand-bushing-stud chain is attached to the tie bars. The chain is set
on the sprockets mounted at the lower shaft. All these creates closed loop
system which when rotating lower shaft sets into rotation flanges together with
Drawing 9. Feed Unit:
1 - worm reduction gearbox; 2 - tooth-type half-clutch; 3 – sprocket