Determination Of The Capabilities To Use Pto Shaft And Cardan Shafts - Belarus 921.6 Operator's Manual

4.8 Determination of the Capabilities to Use PTO Shaft and Cardan Shafts

The mechanical overload-release couplings are used in order to prevent PTO shafts
and PTI shafts breakage in several agricultural machines with active work tools.
The overload-release couplings are intended for automatic discontinuation of
transmission or limiting the value of transmitted torque from PTO shaft to PTI shaft under
overloads, which are caused by high starting torques, overload (blocking) of work tools
and load oscillation on the PTI shaft drive.
ATTENTION: ACTUATION TORQUE OF THE HITCHED MACHINE OVERLOAD-
RELEASE COUPLING SHALL BE HIGHER THAN THE RATED OPERATING TORQUE,
WHICH CONTINUOUSLY PRESENT IN THE MACHINE DRIVE, BUT SHALL ALWAYS
BE EQUAL OR LESS THAN THE MAXIMUM ALLOWABLE TORQUE ON THE TRACTOR
PTO SHAFT SHANK! IF THE MACHINE COUPLING ACTUATION TORQUE IS HIGHER
THAN THE ALLOWABLE TORQUE OF THE TRACTOR PTO SHAFT SHANK, THEN IT
IS PROHIBITED TO HITCH SUCH MACHINE TO THE TRACTOR!
Note – Maximum allowable torques on various types of the BELARUS-921.6 tractor
PTO shaft shanks are specified in subsection 3.2.7 "PTO shaft usage".
The overload-release couplings can be positive-engagement, frictional, disk type
and fall into the two main types - with breakable and unbreakable operating elements. The
couplings with breakable element are used for protection from unlikely overloads.
The overrunning couplings are used in some of the agricultural machines. The over-
running couplings (freewheeling couplings) are automatically lock in one rotation direction
and will release while rotating in opposite direction. The overrunning couplings provide for
operation of machines with increased rotation inertia of the machine rotating masses in or-
der to prevent the drive breakages when the PTO shaft is deactivated.
There are also combined overload-release couplings. The overload-release coupling
is the coupling, design of which is combined with the another type of coupling, for example
with the overrunning coupling.
ATTENTION: THE MANUFACTURER OF THE MACHINE WITH THE CARDAN
DRIVE FROM THE TRACTOR PTO SHAFT SHALL PRELIMINARY INFORM YOU
ABOUT NECESSITY TO USE THE OVERLOAD-RELEASE COUPLING, PARTICULARI-
TIES OF THE COUPLING DESIGN AND CONSEQUENCES OF THE MACHINES US-
AGE WITHOUT THE OVERLOAD-RELEASE COUPLING!
If it is necessary to select (procure) and operate the cardan shaft, then first be gov-
erned by the machine and cardan shafts manufacturer recommendations. We recommend
to use with the tractor machines with active work tools, where length of completely retract-
ed cardan shaft between the joints centres does not exceeds 1 m.
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921.6-0000010 OM