Device for blocking a safety brake for lift equipment

Details Device for blocking a safety brake for lift equipment Device for blocking a safety brake for lift equipment

2002-09-24

2004-10-19

Lillis, Eileen D. (Department: 3652)

Elevator, industrial lift truck, or stationary lift for vehicle

Having means cushioning contact of load support with...

C187S357000

Reexamination Certificate

active

06805223

ABSTRACT:

The present invention relates to lift equipment with a lift cage movable in a lift shaft and with a counterweight movable in the lift shaft, wherein the speed of the lift cage or the counterweight is monitored by means of a speed limiter device and the speed limiter device stops the lift cage or the counterweight by means of a safety brake in the case of excess speed of the lift cage or the counterweight.
BACKGROUND OF THE INVENTION
In the case of lift equipment with a lift cage and counterweight movable in a shaft the speed of the lift cage or the counterweight is monitored. When excess speed occurs the lift cage or the counterweight is stopped by means of a safety brake. If, for example, the lift cage travels beyond the bottom story in the downward direction with less than an excess speed the lift cage is, on further travel thereof, caught by buffers. In that case, the safety brake can be tripped due to the inertia of the speed limiter and the limiter cable, whereby the braking elements of the safety brake wedge with the guide rails.
A disadvantage of known equipment resides in the fact that the lift cage has to be released from the brake. The safety brake has to be reset and the guide rails checked at the braking location and the surface processed. Evacuation of the lift passengers can be undertaken only by expert personnel.
The present invention addresses the disadvantages of the known equipment. The invention includes a speed monitor which applies a safety brake when excess speed of the lift cage or counterweight occurs. A blocking device is associated with the safety brake to block brake action when buffer travel of the lift cage or counterweight occurs.
The advantages achieved by the invention are essentially to be seen in that the safety brake is not tripped in the case of buffer travel. The lift passengers are thus not needlessly exposed to extreme decelerations of the lift cage. Moreover, expert personnel are not needed for carrying out evacuation of the lift passengers.
The lift cage can, after buffer travel, be manually moved to the next story so that the lift passengers can leave the lift cage. Moreover, the mechanical components of the safety brake, and the speed limiter and the guide rails are treated gently. In the case of buffer tests, the safety brake is not tripped and the considerable effort needed for release of the brake is avoided. In the case of approval tests, the safety brake is usually blocked, so that no instances of braking can occur in the shaft end regions in the event of out-of-the-ordinary test travels. With the equipment according to the invention, safety is guaranteed over the entire shaft height even in the case of approval tests.


REFERENCES:
patent: 249076 (1881-11-01), Moulton
patent: 700458 (1902-05-01), Trapp
patent: 1581458 (1926-02-01), Lindquist
patent: 1874754 (1932-08-01), James
patent: 1923683 (1933-08-01), Ohler
patent: 1932060 (1933-10-01), Arnold
patent: 5713434 (1998-02-01), Sun
patent: 5806633 (1998-09-01), Macuga
patent: 59-118678 (1984-07-01), None

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