One-speed double-shaft PTA with ratio i=1.6 is installed on the top hatch of vehicle transfer box. Pinion gear No.1 with two toothed rings is installed on the bottom axle of the transfer box. One of toothed rings (z=36) is in constant engagement with top shaft pinion gear (z=35) of the transfer box; the second toothed ring (z = 26) transmits rotation to sliding pinion No.2 (z=42) installed on splines of top shaft No.3. At shaft (3) outer end there is a safety clutch (4) with shear pin (5); cardan shaft No.1 is fastened to its end (Drawing 2).

Drawing 2 – Kinematic Diagram

1-8, 10 – pinion gears; 9 – gear-shaft; 11 - single-thread worm; 12 – worm wheel; 13-18 – sprockets; 19-21 – gear clutches; 22, 23 – friction clutches; 24-27 - pulleys; А - KAMAZ-740 engine, В - power takeoff attachment; Е – feed unit transmission

If the PTA is overloaded (maximum permissible load is 35 kgm) the pin is sheared. Upon detection of the transmission overload reason the spare pin (5) is installed in the safety clutch. (Drawing 3)

Drawing 3. Power Takeoff Attachment (PTA):

1 – pinion gear (z = 36; z = 26); 2 – pinion gear (z  = 42); 3 - shaft; 4 – safety clutch; 5 – shear pin; 6 – pneumatic cell; 7 - rod; 8 - fork; 9 – spring  

PTA is activated by toggle switch in the cab; through the electro-pneumatic valve the toggle supplies air in the pneumatic cell (6) where rod No.7 shifts pinion gear No.2 by means of fork No.8 to engage into pinion gear (1). Rod is returned by spring No.9.