Backstop; Cooling; Fan - Siemens Flender H2NV Series Assembly And Operating Instructions Manual

5.7

Backstop

For certain requirements, the gear unit may be fitted with a mechanical backstop. This backstop permits
only the specified direction of rotation during the operation of the unit. The direction of rotation is marked
by a corresponding arrow on the input and output side of the gear unit.
The backstop is integrated in the gear unit and is supplied with oil by its oil circuit.
The backstop is fitted with centrifugally operated sprags. If the gear unit rotates in the prescribed direction,
the inner ring rotates with the sprag cage in the direction of shaft rotation, while the outer ring remains
stationary. From a specific speed up (disengagement speed) the sprags disengage from the outer ring.
In this operating condition the backstop operates wearfreely.
Fig. 12: Backstop
1 Outer ring
2 Inner ring
The stop direction can be changed by turning the cage around. If a change in stop direction is
required, Siemens should be consulted beforehand.
To avoid damaging the backstop or the gear unit, the motor must not be run adversely
to the stop direction of the gear unit.
Observe the notice fixed to the gear unit.
The backstop must be replaced after 10 000 operating hours!
If the gear unit is operated at speeds below the speed at which the backstop
disengages, the backstops must be regularly renewed. The frequency of change is
stated on the dimensioned drawing prepared in accordance with the order and on
a plate on the gear unit. This plate is attached to the gear­unit housing close to the
backstop.
Before connecting the motor, determine the direction of rotation of the three­phase current supply using
a phase­sequence indicator, and connect the motor in accordance with the pre­determined direction of
rotation.
5.8

Cooling

Depending on requirements, the gear unit is fitted with a fan.
When installing the gear unit free convection must be ensured on the housing surface, in order
to definitely avoid overheating the gear unit.
5.8.1

Fan

As a rule the fan is fitted on the high­speed shaft of the gear unit and is protected from accidental contact
by cover plates. The fan sucks air through the grid on the cover plates and blows it along the air ducts on
the side of the gear­unit housing. It thereby dissipates a certain amount of heat from the housing.
1
2
3 Cage with sprags
4 Shaft
BA 5060 EN 04/2011
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4
3