Electric Lift – Potential Brake Problem

Figure 1: An example of typical electromagnetic brake arrangement at electric lift motor

This safety alert is intended for any person involved with installation,inspection,examination,testing and maintenance of electric lift. There have been incidents (in 2011 and 2012) where the electromagnetic brake failed to function properly, causing the lift car to suddenly crash. These cases may have been caused by the failure of the brake pads to be applied; the plunger (inside the electromagnetic device) got stuck and failed to close the brake lever arm; and the lever arm for the pivot pin got jammed during its activation because of some inherent defects.

Recommended Actions:

Therefore, the following actions are recommended:

1. Lift maintenance service company must ensure that proper lubrication is applied to any joint of the moving parts, especially for the electromechanical braking system. This activity must be consulted with the relevant lift manual and manufacturer regarding the detail of maintenance required (e.g. type of maintenance, maintenance part/point, lubrication type, interval frequency, etc).
2. Proper documentation system must exist to support the above exercise. This will also provide transparency and enable audit checks to ensure the integrity of the maintenance program.
3. The supervisor must monitor and check on the work done, as well as assess the understanding of their technicians in carrying out the task to ensure that the task is carried out satisfactorily.
4. Refresher technical courses on the correct adjustment, oiling, inspection and testing of the electromagnetic brake mechanism shall be conducted for enhancing the knowledge and skills of the lift servicing personnel.
5. The electromagnetic brake mechanism shall be tested and examined once every three months by the lift competent personnel registered with the department. His observation shall be recorded in the lift register.

Further readings:

1. Howkins, R.E. 2006. Lift modernisation design guide. Elevator World, Alabama, USA.
2. Annet, F.A. 1989. Elevators – electric and electrohydraulic elevators, escalators, moving sidewalks, and ramps. McGraw-Hill, New York, USA.
3. Janovsky, L. 1999. Elevator mechanical design, 3^rd edition, Elevator World, Alabama, USA.

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