Torque­limiting Backstop (Special Design) - Siemens FLENDER H SH Series Assembly And Operating Instructions Manual

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.
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.
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 of the gear unit and on a plate on the gear unit. This
plate is attached to the gear­unit housing close to the backstop.
5.9 Torque­limiting backstop (special design)
A torque­limiting backstop is available for special uses, e.g. dual drives. The backstop is a combination
of a backstop with centrifugally operated sprags and a brake. The slipping torque is set by a number of
compression springs.
This "slipping" will protect the gear unit and the sprags of the backstop from inadmissibly high stresses
during negative rotation. In addition, a uniform load distribution onto both gear units is achieved during
negative rotation when using dual drives.
Fig. 20: Torque­limiting backstop
1 Outer ring
2 Inner ring
3 Cage with sprags
4 Shaft (adapter flange)
The torque­limiting backstop is attached to the gear unit by means of an adapter flange to form an oiltight
seal and is integrated in its oil-circulation system.
The stop direction can be changed by turning the cage around. If a change in stop direction is
required, Siemens should be consulted beforehand.
The slipping torque was set at the correct value during the manufacturing process resetting
during startup is not permissible.
To safeguard the set slipping torque, the lead screws of the compression springs are secured
with locking wire. The warranty will expire if the locking wire for the screws is missing or has
been damaged.
6
4
3
7
x
min.
5 Locking wire
6 Lead screw with compression spring
7 Friction lining
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