The gearbox generates three different rotation speeds of rotary table and drawworks drums.
The shafts, pinion gears and clutches are placed in the gear casing No. 21 (Drawing 5)
The left end of the driven shaft leans on the ball-bearing (1) placed in cage (3). The bearing cup thrusts upon cage collar and clamped by the cover (2). The cage is fixed to the gear casing by screws. Between gear casing and cage flange there is a set of two-millimeter adjusting shims mounted.
Pinion gears (5, 6 and 7), separated by distance bushes, are fixed by washer through the bearing inner race and the spacing disk. The washer is fastened to the shaft face by screws.
The right end of the driven shaft is arranged on the roller-bearing (8) the
inner race of which is fastened by the nut (16) through the bevel pinion (9)
hub. The pinion gear is hold at the shaft by prismatic wedge key (10). The nut
(16) is screwed by the lock washer.
Drawing 5. Gearbox:
1, 12, 19 Ц ball-bearing; 2 - cover; 3 - cage; 4 - ring; 5, 6, 7, 18 Ц pinion gears; 8 - roller-bearing; 9, 26 - bevel pinion gear; 10 Ц wedge key; 11 - clutch; 13, 28 - shafts; 14 - pump; 15 Ц pump drive roll; 16 Ц nut; 17 Ц pinion gear assembly; 20 Ц drive shaft; 21 Ц gear casing; 22, 25 - forks; 23 Ц bottom slide roll; 24 Ц top slide roll; 27 - probe; 29 - sprocket; 30 - clutch; 31 Ц collar plate
Driven shaft unit with one end fixed in the ball-bearing permits axial movement of the second end.
On the driven shaft there is a gear clutch (11) to activate rotary drive shaft (13). The shaft is on spherical ball-bearings (12).
The drive shaft of the gearbox is mounted on ball-bearings (19). The pinion gear (18) of the 1st gear and pinion gear assembly (17) of the 2nd and 3rd gear are mounted onto the drive shaft (20) splines. The pinion gears are shifted by the forks.
Oil pump drive roll (15) is inserted into the right end of drive shaft and is hold by roll pin.
Power takeoff for the drawworks is realized via shaft No.28.
At one end of the shaft there is a movable gear clutch (30); it is engaged into mesh with teeth of sprocket hub (29) of drawworks shaft drive by the collar plate (31).
The clutch is hold by the washer fixed to the shaft face by the screws.
Gear-shift is realized by forks No.22 and 25. The shift fork (22) for second and third gears is fixed on the bottom slide roll (23) by screw. The first-gear shift fork (25) is fixed on the top slide roll (24) by screw.
The gear shift mechanism is equipped with fixing device which prevents simultaneous activation of two gears.
Gearbox lubrication is oil bath lubrication.
The oil is supplied into the gearbox through the breather; oil level is controlled with the probe (27).