2 replies to this topic

[Bill]

2.3.7 Brakes

The brakes serve several purposes:

To decelerate (stop) the ropeway in the event that electrical braking does not provide sufficient deceleration; initiated if one of the "Service Stop" or "Emergency Stop" buttons is pressed, or if a control device is tripped.

To hold the ropeway at a standstill (during breaks in operation or shutdowns).

To regulate rope speed when clearing the line using an overhauling load (manoeuvring).

The braking force is transmitted to the haul rope via the bullwheel. As far as the transmittable braking force is concerned, the same physical principles apply as those already described for the transmittable driving force.

Circulating monocable ropeways are equipped with two brakes (service brake and emergency brake) which are connected to separate control circuits.

 Brake_System.jpg (93.55K)
Number of downloads: 70

Once activated, these brakes are automatically engaged and apply the same braking force in both directions of rotation. Both brakes operate according to the "normally closed" principle.

[Bill]

Service brake

The purpose of the service brake is

1. to stop the ropeway if one of the monitoring devices which initiates a "Service Stop" or an "Emergency Stop" is triggered,

2. to hold the ropeway at a standstill once a "Stop" command has been activated or if a minimum speed is not reached and

3. to regulate rope speed when operating the ropeway manually with a rescue drive.

As a rule, the service brake is a disk brake and is installed on the high-speed shaft of the drive system. This means that the brake becomes ineffective in the event of gearbox failure.

Emergency brake

The purpose of the emergency brake (also referred to as the main brake) is

1. to stop the ropeway in the case of an "Emergency Stop" button having been pressed,

2. to hold the ropeway at a standstill when it has been shut down,

3. to stop the ropeway if the manual valve of the emergency brake is actuated and

4. to regulate rope speed (manoeuvring) when clearing the line with an aid of an overhauling load using a hand pump and a manual valve.

This brake is a disk brake which acts directly on the drive bullwheel or on a ring gear integrated into the bullwheel. Configurations exist which include a mechanism allowing manual closure of the brake.

 Emergency_Brake.jpg (99.95K)
Number of downloads: 48

[Bill]

Backstops and anti-rollback brakes

These prevent the ropeway from rolling backwards following a stop when loaded on one side only.

Mechanical backstop on gearbox input shaft

In the case of chair and gondola lifts these backstops are designed for disengagement to allow testing of the emergency and service brakes. The advantage here is the reduction in the amount of torque to be taken up as a result of the gearbox transmission. The disadvantage is poor accessibility for inspection purposes, the jerking action on engagement and the ineffectiveness in the case of gearbox failure.

Mechanical backstop or anti-rollback brake on bullwheel

There are two basic forms of construction:

1) Backstop with one or more ratchets which act directly on the drive bullwheel if the ropeway rolls backwards.

2) Anti-rollback brake as an additional brake on the drive bullwheel which engages if the ropeway rolls backwards or is triggered by an overspeed monitor in the case of a downhill load.

Anti-rollback brakes have the advantage that they do not engage abruptly. they allow adjustment of the deceleration rate.