US3507368A - Braking device for gate - Google Patents

Description

Ap 21, 1970 H. DURANT 3,507,368 7 BRAKING DEVICE FOR GATE Filed Feb. 21, 1968 Hgnr/ DU/PAN,

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United States Patent Int. Cl. F16d 55/02 US. Cl. 188-164 3 Claims ABSTRACT OF THE DISCLOSURE A braking device for gates, particularly a railroad crossing gate comprising a disc, having a flat face, mounted on the articulation shaft of the gate. An electromagnet is mounted in close relationship with the flat face on a support mounted for articulation about an axis parallel to the fiat face. The electromagnet includes at the ends of the magnetic core a pair of pole pieces in the form of plates the edges of which adjacent the disc flat face are provided with brake linings. The articulation axis lies between the disc fiat face and a vertical through the center of gravity of the support and arranged to cause articulation of the support and electromagnet away from the disc when the coil is deenergized.

The present invention relates to an electromagnetic braking device adapted to hold a gate, for instance a railroad crossing gate, in predetermined positions by energization of a coil through which a DC. current flows.

The braking device according to the invention is particularly appropriate to gates for full-width railroad crossings with automatic control independent of signal blocks that regulate traffice on the road; any accidental break in the energization circuit of the braking device resulting in the fall of the gate. The braking device may oppose an appreciable torque while consuming very little power. There is hardly any lateral forces reacting on the shaft of the driving motor for lifting the gate. Finally, the braking device is not bulky.

The braking device according to the invention is characterized in that it comprises a flat circular disc mounted on the horizontal shaft of the motor device for lifting the gate, a support articulated about an axis parallel to the fiat face of the said disc, carrying a coil provided with a magnetic core parallel to the said axis and having two pole pieces in the form of parallel plates against the cheeks of the coil, the edges of the plates being disposed at a short distance from the disc, provided outwardly with a thickness of Ferodo adapted to be applied against the disc when the pole pieces are drawn toward it, the articulation axis of the support being located between the vertical through the center of gravity of the support and the disc. -Z

The invention will be better understood from the following description of a preferred embodiment having reference to the appended drawing illustrating a braking device according to the invention.

,The single figure is a perspective view illustrating a motor device 1 adapted to actuate a non-illustrated gate and provided with a horizontal shaft 2. A circular disc 3 is mounted on shaft 2 and has a flat outer face located a short distance from the pole pieces 4 of an electromagnet having a coil 6 surrounding a core 5. This electromagnet is mounted on a support 7 that articulates about axle 8 solid with a bracket 9 secured to the frame of the motor device 1 by means of a U-shaped sheet metal member .10 and screws (not shown on the drawing) for adjusting its position. A Ferodo brake lining 12 is provided Ill 3,507,368 Patented Apr. 21, 1970 on the outer edge of each pole piece 4, held thereagainst by a plate 13 secured by screws 14 to the pole piece. Brake lining 12 projects beyond the edge of the pole piece 4 so that when the latter is drawn toward disc 3, it is Ferodo lining that comes in contact with it. Safety lugs (not shown) made of non-magnetic metal prevent direct contact of the pole pieces with the disc when the Ferodo linings are worn out to a certain extent to thus avoid sticking. The articulation axis 8 is located between the disc 3 and the vertical thruogh the center of gravity of the support 7 in such a way that the weight of the latter draws it away from the disc when the coil 6 is not energized. A non-illustrated spring adds its action to that of gravity to draw the support away from the disc so as to give more stability to this position. This spring also serves to limit the pivoting movement of the support 7. It is secured to the latter by means of a screw 11 and, on the other hand, fastened onto frame 10 by any other convenient means.

When coil 6 is energized by a DC. current, the pole pieces 4 are drawn by the disc 3 and apply their Ferodo linings whereby disc 3 is stopped and, consequently, the gate. By braking the energization of coil 6, the gate falls back through its own weight while actuating its driving motor which, working as a generator, discharges through a resistance whereby to smoothen the fall of the gate.

It is to be noted that, by the vertical orientation of the Ferodo linings, the braking forces practically result into two vertical components equal and opposite to one another so that braking does not create appreciable forces on the driving axle.

I claim:

1. An electromagnetic braking device for a gate, particularly a railroad crossing gate actuated by a motor having a horizontal shaft, comprising: i

(a) a magnetizable braking disc mounted on said shaft and having a flat face;

(b) an electromagnet including a coil, a magnetic core extending through said coil and parallel to said braking disc and pole pieces in the form of j plates flat against each end of said core, said pole pieces each having one edge adjacent said disc;

(0) brake lining on said edges to come against said disc when said coil is energized and said pole pieces are drawn towards said disc; and

(d) a support for said electromagnet, said support having an articulation axis parallel to said disc and lying below the center of gravity of said support, said articulation axis being located between said disc and a vertical through said center of gravity whereby, upon deenergization of said coil, the weight of said support causes said pole pieces to move away from said disc under the forces of gravity.

2. A braking device as claimed in claim .1, including means to restrict movement of said .pole pieces away from said disc. 2

3. A braking device as claimed in claim 1, wherein said brake linings are in the form of elongated parallel vertical strips disposed on either side of said motor shaft whereby to prevent the creation of any appreciable lateral forces to act against said shaft.

References Cited UNITED STATES PATENTS 750,207 1/1904 Lockwood .5188-164 1,812,190 6/1931 Baseler 1 1 88-164 X 2,131,888 10/1938 Harris.

DUANE A. REGER, Primary Examiner US. Cl. X.R. 188-71

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