Autoquip FREIGHTLIFT FLM - Manual (Page 12)

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There are several primary active safety features and devices to help protect personnel,
property, and the equipment.
LOCKING CAMS (Reference Figure 19)
Each chain is terminated at the platform carriage in a clevis, which is attached to a
tension spring loaded steel safety cam. This safety cam pivots on a high strength steel
pin which is chrome plated. The safety cam has serrated teeth cut into one of its faces
that are adjacent to the guide beam flange.
Should the chain become slack, the spring tension would cause the serrated teeth of
the safety cam to engage the guide beam. The teeth bite into the guide beam and a
wedging effect takes place between the safety cam and the guide beam. The result is a
positive halt to downward movement.
The only way to release the safety cam is to correct the malfunction that caused the
slack chain and exert upward tension on the chain through the chain drive. Either of the
two cams will support the loaded platform carriage at any point in the vertical travel.
WARNING !
Slack chains require factory help! Do not attempt to repair slack chain
conditions alone! Always contact the local representative or call the
Autoquip Service Department.
SLACK CHAIN SENSORS (Reference Figures 33)
The slack chain sensors are located on the drive base. The sensors are made up of a
mechanical spring tensioner with a nylon roller and an electrical sensing switch. The
lifting chains run over the sprockets on the main shaft, beside the slack chain sensors,
and then to the carriage. The carriage holds the chains in constant tension. The
sensing switch arm is adjusted to hold the sensing switch contacts closed as the
tensioner roller is running against the taut chain. Should a chain become slack or
broken, the spring tensioner would rotate and activate the sensing switch arm to open
its normally-closed electrical contacts. This would break electrical power to the drive
motor and cease movement of the carriage. The lift will not operate until each slack
chain sensor is restored to its correct operating condition. There is one (1) slack chain
sensor per lifting chain.
CARRIAGE OVER-TRAVEL LIMIT SWITCH (Reference Figure 30)
A redundant, over-travel limit switch is provided to be field located and installed beneath
the drive base in order to stop the motor should the carriage not stop at the upper level
limit switch location (due to faulty wiring, out-of-adjustment or damaged limit switch
arm, etc.). Making of this switch would break the electrical circuits, shut off the motor,
and cease movement of the carriage. The carriage will not move until the
over-travel limit device is restored to its correct operating condition.
SAFETY FEATURES