Brakes – Rod
Reexamination Certificate
1998-12-21
2001-03-27
Oberleitner, Robert J. (Department: 3613)
Brakes
Rod
C187S207000, C187S272000, C188S256000, C188S25000B, C188S26400E
Reexamination Certificate
active
06206145
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to brake shoes for a brake apparatus utilized to stop a hydraulic elevator. The brake apparatus is provided for the locking of a piston carrying an elevator car or a cable pulley and guided in a hydraulic cylinder. The brake apparatus has a pair of brake arms tiltable by means of a brake drive, one of the brake linings being arranged on each brake arm, which brake linings are moved into engagement with the piston when the arms are rotated to a braking position.
In the International patent application no. PCT/US96,/15901 International publication no. WO 97/12829, there is shown a braking device for a hydraulic elevator in which brake arms are provided for enclosing the piston of a hydraulic cylinder. At unauthorized lowering movements of the piston, the brake arms are tilted downward by means of a brake control, where semicircularly shaped brake linings of the brake arms lock around the piston and clamp the same. It is a disadvantage of this known device, that for the inward and outward tilting movement of the brake arms relatively great forces are necessary.
SUMMARY OF THE INVENTION
The present invention concerns a brake apparatus having a pair of opposed brake arms pivotally mounted at respective pivot points adjacent a piston of a hydraulic elevator drive. The brake apparatus also includes a vertically slidable plunger attached to the brake arms for pivoting the brake arms about the pivot points and a beam upon which the brake arms are pivotally mounted, the beam being adapted to be mounted on the upper end of the hydraulic cylinder guiding the piston. A semicircular brake lining is attached to each of the brake arms for engaging the surface of the piston and at least one shoulder is formed on an inwardly facing surface of each of the brake linings providing a transition between a piston contact portion an a recessed portion that does not contact the piston. The shoulder is positioned in the same horizontal plane as the pivot point of the associated brake arm. As the brake arms are pivoted about the pivot points toward the piston, a portion of each of the shoulders initially engages the surface of the piston thereby minimizing forces applied to the pivot points and the piston through the brake arms. At least one oil channeling groove can be provided adjacent the shoulder for carrying off hydraulic oil on the piston to increase the friction between the piston surface and the brake lining.
The brake apparatus according to the present invention solves the problem of avoiding the disadvantages of the known braking devices and provides a braking device with an increased braking effect.
An advantage of the brake apparatus according to the present invention is that reduced starting forces are necessary for the inward and outward tilting motions of the brake arms it the moments of engagement and disengagement respectively.
It is a further advantage that the braking forces are distributed more evenly over the surface of the brake linings. Also, larger frictional forces are achieved between the brake linings and the piston whereby the piston and thus also the elevator car can be stopped with a lower surface pressure.
REFERENCES:
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patent: 3647027 (1972-03-01), Jaseph
patent: 3762512 (1973-10-01), McIntyre
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patent: 3783983 (1974-01-01), McNally et al.
patent: 3995534 (1976-12-01), Rastetter
patent: 4007815 (1977-02-01), Acre
patent: 4306339 (1981-12-01), Ward
patent: 4449615 (1984-05-01), Beath et al.
patent: 4715456 (1987-12-01), Poe, Jr. et al.
patent: 4823919 (1989-04-01), Hayatdavoudi
patent: 5810119 (1998-09-01), Koshak
patent: 5964320 (1999-10-01), Kato et al.
patent: 6039151 (2000-03-01), Ringel et al.
patent: WO 97/12829 (1997-04-01), None
Innovation: Jack Arrester, Feb. 1996, Elevator World, pp. 50-52.
Cable Edward G.
Jodry Dean L.
Stewart Richard A.
Inventio AG
Kramer Devon
MacMillan Sobanski & Todd LLC
Oberleitner Robert J.
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