Belarus 3522.5, Operator'S Manual

Page: 254 / 340

3522.5-0000010 OM
255
For the purpose of torque test on PRS and in case you know PTO shaft rotation
speed and PRS takeoff power nomographic chart (Figure 5.7.1) or the following formula
can be used:
where M is torque, Nm; P is PRS takeoff power, kW; n is PTO shaft rotation speed,
min
-1
.
ATTENTION: NOMINAL ROTATION SPEED OF PRS END OF THE IMPLEMENT
COUPLED SHALL NOT EXCEED 1000 MIN
-1
!
If there is a need to improve the PRS rotation speed or rotation speed of working at-
tachments for the implements coupled the following formula can be used:
n
pic
= un
s
where n
pic
is PRS rotation speed, min
-1
; n
s
is working attachments rotation
speed, min
-1
; u is gear transmission ratio of the implement drive.
To avoid failures of PTO shaft and PRS in several implements with active working
attachments (tilling rotary implements, combine harvester, mowers, cattle-feeders, pickup
balers and etc.) mechanical safety clutches are used.
Functional purpose of the safety clutch is automated gear deactivation or limitation
of the torque value transmitted from the PTO shaft to PRS under overloads caused by
large starting moment, overload of (locks) the working attachments and loads fluctuations
on the PRS drive.
Response time of the implement cardan shaft safety clutch can be by the following
formula:
М
с
= k·
М
1
≤ М
PTO
where
М
PTO
is maximum permissible PTO shaft torque, Nm;
М
с
is response time of
the safety clutch, after which the implement shall not operate, Nm;
М
1
is nominal operating
torque, permissible for the implement drive in the specified operating conditions, Nm; k =
1.25…1.5 is design factor (smaller values are taken for low-duty conditions and the bigger
ones – for heavy conditions).
ATTENTION: THE IMPLEMENT COUPLED SAFETY CLUTCH RESPONSE TIME
SHALL EXCEED THE NOMINAL OPERATING TORQUE ACTING FOR A LONG TIME IN
THE IMPLEMENT DRIVE, BUT BE ALWAYS EQUAL TO OR LESS THAN THE MAXI-
MUM PERMISSIBLE PTO SHAFT TORQUE! IF THE IMPLEMENT SAFETY CLUTCH
RESPONSE TIME EXCEEDS THE PERMISSIBLE PTO SHAFT TORQUE SUCH IM-
PLEMENT MUST NOT BE COUPLED WITH THE TRACTOR.
Among safety clutches there are cam clutch, frictional clutch, disk clutch, they can
be subdivided to two basic types – with destructible and indestructible working compo-
nents. Clutches with a destructible component are used as overload control device.
ATTENTION: IT IS NOT RECOMMENDED TO USE CARDAN SHAFTS WITH
SAFETY CLUTCHES WITH A DESTRUCTIBLE COMPONENT ON THE TRACTORS
“BELARUS-3522.5”!
In several implements freewheeling clutches are used. The freewheeling clutches
(sprag clutches) are automatically closed if the rotating direction is straight, and are un-
closed if the rotating direction is opposite. The freewheeling clutches ensure operation of the
implements with the increased inertia moment of the implement rotating masses to prevent it
from the drive failure when the PTO shaft is switched off.
There are also combination safety clutches. A combination safety clutch is the safety
clutch which is structurally combined with a clutch of other type, for example with a free-
wheeling clutch.
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