16
MHD56490
Overload Device
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This overload protection device is factory set at 125% maximum of the SWL at rated layer. Refer
to
.
The overload device is integrated into the winch air motor and prevents the winch from lifting a load greater than
the winch nominal overload setting. When an overload is detected, inlet supply air is stopped and the winch will not
operate. If the overload device is activated the load must be lowered and reduced. Alternative methods should be
used to accomplish the task. Refer to
“Emergency Stop and Reset,” p. 15
. To lower the load, first reset the winch by
pressing the “RESET” button of the emergency stop valve and operate the winch control for wire rope payout.
Remote Pendent
Refer to
Provides remote winch control at distance up to 20 meters (66 ft) away from the winch motor. Pilot air hoses
connect the pendent to the winch motor to provide winch operation. The pendent control throttle is a two lever
movable control station. Direction of winch drum rotation is determined by the pendent control lever depressed.
Winch Brakes
Automatic Disc Brake
The automatic disc brake is a spring applied, air released brake. When the control valve is in the neutral position,
the air in the brake is vented and the brake is engaged. The springs, acting on the pressure plate, compress the
brake friction and separator plates and engage the brake to prevent drum rotation.
Automatic Drum Band Brake
The automatic drum band brake is a spring applied, air released, externally mounted brake. When the control valve
is placed in the neutral position, the air in the cylinder is vented allowing the spring tension to automatically engage
the brake and prevent drum rotation.
Emergency Lowering
This device allows the person to be lowered safely in case of main air supply failure.
Note:
Recommended minimum load for Emergency Lowering is 200 lbs (91 kg).
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• This is a two person procedure, one person to operate the emergency lowering device, the
other to maintain a line of sight on the person being lowered.
• The winch must be isolated from the main supply air system during this operation. Make
sure the Emergency Stop button is pressed down and latched in the OFF position.
• Communication must be established between the lifted person and winch operators.
Operators should be able to visually monitor lifted person until landed.
• If line of sight between operators and lifted person is not possible, signals must be conveyed
to the operators.
Emergency Lowering Procedure
Refer to
1. In the event of air supply failure, press the Emergency Stop button to the down and latched OFF position.
2. Actuate and hold the switch nearer to the motor. Switch #1 on
. This will release the Disc Brake.
Then actuate the switch further from the motor. Switch #2 on
. This will release the Band Brake.
Toggle this switch as necessary to control the descent of the person, while continuing to hold Switch #1 in the
actuated position.
3. The signal-person shall maintain the line of sight of the person being lowered to make sure the person is not
being entangled in wire rope or other equipment on the rig. The signal person shall alert the operator to release
Switch #2 to stop lowering temporarily to avoid hazards, as necessary.
4. Continue to hold both the switches in the actuated position in order to lower the person safely to the ground.
