US2188521A - Hand brake mechanism - Google Patents

Description

Jan. 30, 1940. w ZANE HAND BRAKE MECHANISM Filed Aug. 25, 1938 :s Sheets-Sheet 1 Jan.30,1940l, E. w. ZA E 2,1 8,521

HAND BRAKE MECHANISM,

Fi led Aug. 25. 1958 v s Sheets-ShetZ- Patented Jan. 30, 1940 UNITED STATES PATENT OFFICE Application August 25, 1938, Serial No. 226,665

13 Claims.

My invention relates to hand brakes for railway cars and more particularly to the operating or control mechanism therefor.

In those types of hand brakes wherein suitable gearing is interposed between the hand wheel and the brake chain to provide the required leverage for setting the brakes, it is customary to incorporate a ratchet-pawl mechanism. which is automatically engaged when the hand wheel is rotated in a brake setting direction to hold the brake shoes in any determined position. Some provision is further made to secure the release of the pawl when desired. In general, only a single pawl is employed which not only unbalances the load application on the ratchet, but is also subject to the further objection that, in the event of breakage of the pawl, the mechanism is thrown out of service.

It is therefore one object of my invention to provide a hand brake mechanism having two pawls which are disposed to substantially equalize the load on the ratchet during the application of the brakes and which are moved simultaneously into and out of engagement with the ratchet.

A further object is to devise a hand brake mechanism of the character indicated in which ing in the direction of the arrows;

Figs. 2 and 3 are sections along the lines 2-2 and 33 in Fig. 1, looking in the direction of the arrows;

Fig. 4 is a fragmentary elevation of the device as it appears in position on a railway car, looking in the direction of the arrow 4 in Fig. 3; I

Figs. 5 and 6 are sections along the line 55 in Fig. 2, looking in the direction of the arrows, showing, respectively, the engaged and released positions of the pawls.

Referring to. the drawings, the numeral Ill designates the usual brake chain, one end of which extends beneath the body of the car in the customary manner for affixation to the braking anism taken along the line l-l in Fig. 2, looksystem (not shown) while the other terminal link is connected to a pin II that is mounted in and extends laterally from a spoke of a spur gear [2. The gear is journaled on a shaft l3 whose ends are supported by the opposite walls of an enclosing housing l4 having a plurality of lugs l5 through which suitable bolts extend for securing the housing to the end wall of the car body 16. The housing prevents impairment of the operation of the mechanism by ice, sleet and snow, or foreign matter such as coal, stones, etc.v Also freely journaled on the shaft l3 beside the gear I2 is a reeling roller ll that may have its peripheral surface appropriately grooved to receive alternate lengths of the brake chain during the winding operation, as hereinafter described.

The gear l2 meshes with a pinion l8 that may be integrally formed with an operating shaft l9 whose rear end is journaled in the rear wall of the housing I4 and whose intermediate portion is journaled in a plate that is supported from a plurality of ears 2| adjacent the front side of the housing M. The front end of the shaft l9 extends through an opening in a cover plate 22 and has aiiixed on the end thereof a hand wheel 23 that is of the so-called vertical type. However, it will be understood that the mechanism which forms the subject matter of my invention is not restricted to use with vertical hand wheels, but

- also may be employed in connection with those of the horizontal type.

Also integrally formed with the operating shaft [9 is a ratchet wheel 24 and a pair of pawls 25 and 26 are symmetrically disposed with respect to the ratchet wheel so as to engage with the teeth thereof at opposite sides of the wheel, or substantially at the ends of any diameter thereof. By this provision, it is possible to equalize or balance the load application on the ratchet. The pawl 25 is of the tension type, while the pawl 26 is of the compression variety and may be integrally formed as a part of a shaft 21 whose ends ar journaled in the rear wall of the housing l4 and in the plate 20, respectively (see Fig. 3). The pawl 26 is provided with a bifurcated arm 28 that extends toward the pawl 25 which in turn is provided with a tooth 29 that is cooperatively related to the arm 28 so that when the pawl 25 is operated as hereinafter described like movements will be imparted to the pawl 26.

The pawl 25 is provided with a hub 30 that is freely journaled on a shaft 3! whose ends are carried by the rear wall of the housing l4 and th plate 20, respectively, the front end of the shaft extending through the cover plate 22 for. its

securement to a release actuating handle 32. The pawl hub 39 is provided rearwardly with a sector lug 33 whose ends form rotarily spaced abutments 34 and 35. A similar sector lug 36 may be integrally formed with the shaft 3i and the ends thereof form rotarily spaced abutments 3? and 38. The sector lugs 33 and 36 are positioned in the same plane of rotation and when the pawls are engaged and the handle is in the position shown in Fig. 4, the abutments 34 and 3'! are in contact, while the abutments 35 and 33 are spaced apart. This condition is illustrated in Figs. 1 and 5. A stop nose 39 may also be integrally formed on the shaft 3! in axially spaced relation to the sector lugs and this nose is intended to engage with a shoulder id on the housing I l to limit the releasing movement of the handle 32 as hereinafter described.

In Fig. l, the pawls are shown engaged with the ratchet wheel 25, with the release handle occupying the position shown in Fig. l, but no tension has been applied to the brake chain it. To set the brakes, the operator rotates the hand wheel 23 in a clockwise direction, as viewed in Fig. 1, and during this operation the par/is and 26 merely slip over the teeth of the ratchet in the customary manner. When the required tension has been established in the brake chain E6, the pawls are fully engaged with the ratchet wheel and thus maintain the established setting of the brakes. The relation of the pawls and the ratchet wheel is then substantially as illustrated in Fig, 1 and particular attention directed to the balancing of the load on the ratchet wheel which provides a better stress distribution in the ratchet wheel in comparison with previous devices employing single pawls.

When it is desired to release the brakes, the operator first moves the rel-ease handle 32 from the positon shown in Fig. 4 to that indicated by the numeral 6! in Fig. 6. This movement or" the handle may be accomplished freely until the abutment 38 contacts the abutment 35 when further movement of the handle in the indicated direction is resisted by the friction between the pawls and the teeth of the ratchet wheels. At this juncture, it will be noted from an examination of Fig. 6 that the release handle occupies a position above and to the right of the axis of the shaft 3!. The operator then slightly rotates the hand wheel 23 in a winding or clockwise direction sufiiciently to relieve the friction between the teeth of the ratchet and the pawl, this po sition of the ratchet being gene ally indicate by dotted lines in Fig. 6. The pawls being thus freed for movement, are shifted to the positions indicated by dotted lines in- Fig. 6 by the gravity movement of the release handle which assumes the position designated by the nrnneral 32 and one in which further movement in a releasing direction is limited by engagement of the nose 39 with the shoulder H3. The toothed or interconnected relation between the pawls and 2S insures that both of the pawls will be simultaneously moved to release positon. As soon as the handle has moved the small angular distance indicated in Fig. 6, as can be observed by the operator, it is merely necessary for his grip to be released from the hand wheel to permit the same to spin in the usual manner and relieve the brakes.

As already stated, the fully released position of the pawls is indicated by the numeral Fig. 6. At this time, the abutments on are in contact, while the abutments 3-; and

so i:

are spaced from each other. To again place the pawls in engagement with the ratchet wheel, the release handle is moved from the position represented by the numeral 42 in Fig. 6 to that shown in Fig. 4, being the same as that indicated by the numeral 413 in Fig. 6, and, during this movement, the pawls automatically engage the ratchet due to the fact that they are hung for self-ratcheting action. The handle 32 when in the position shown in Fig. 4 assists in maintaining the pawls in ratcheting engagement, while the contactin or" the abutments 3t and 3'! serves to limit further movement of the handle in the indicated direction.

The use of the twin pawls contributes to the safety characteristics of the device, as does the fact that when setting and relieving the brakes, the operator may keep both hands firmly gripped on the hand wheel .23 and need not have his attention distracted by the necessity for handling other portions of the apparatus. 7

I claim:

1. Hand brake mechanism comprising in combination, a rotatable ratchet adapted for connection to a winding device, a pair of pivoted and interconnected pawls operatively related to the ratchet, and actuating means freely rockable in one direction to contact one pawl and thereby engage both pawls with the ratchet and in the opposite direction to contact said one pawl when further movement of the actuating means is resisted by friction between the pawls and ratchet teeth, the actuating means having a weighted portion causing further rotation thereof in said opposite direction under the action of gravity to release the pawls when said friction is relieved by a rotation of the ratchet in a winding direction.

2. i-land brake mechanism comprising in combination, a rotatable ratchet adapted for connection to a winding device, a pair of pivoted and interconnected pawls o eratively related to the ratchet, and actuating means freely rockable between a limiting position in which the pawls are engaged with the ratchet and a temporary limiting position in which movement or" the means is resisted by friction between the pawls and ratchet teeth, the actuating means having a weighted portion causing further rotation thereof in said resisted direction under the action of gravity to release the pawls when said friction is relieved by a rotation of the ratchet in a winding direction.

3. Hand brake mechanism comprising in combination, a rotatable ratchet adapted for connection to winding device, a pair of pivoted and interconnected pawls operatively related to the ratchet and hung for self-ratcheting action, one of the pawls having a first pair of rotarily spaced abutments, and rockable pawl actuating means having a second pair of rotarily spaced abutments located in the plane of rotation of the first abutments, the actuating means being freely rockable in one direction to permit the pawls to engage the ratchet and to contact an abutment thereof with a pawl abutment to limit movement of the actuating means, and in the opposite direction to contact the other abutments when further movement of the actuating means is resisted by friction between the pawls and ratchet teeth, the actuating means having a weighted portion causing further rotation thereof in said opposite direction under the action of gravity to release pawls when the friction is relieved by a rotation .of the ratchet in a winding direction.

4. Hand brake mechanism comprising in combination, a rotatable ratchet adapted for connection to a winding device, a rock shaft, a pair of pivoted and interconnected pawls operatively related to the ratchet and hung for self-ratcheting action, one of the pawls being freely rotatable on the shaft and having a first pair of rotarily spaced abutments, a second pair of rotarily spaced abutments provided on the shaft and located in the plane of rotation of the first abutments, and an actuating handle secured to the shaft, the handle being freely rockable in one direction to permit the pawls to engage the ratchet and to contact a shaft abutment With a pawl abutment to limit movement of the handle and in the opposite direction to contact the other abutments when further movement of the handle is resisted by friction between the pawls and ratchet teeth, the handle in said last-named position being adapted for further movement under the action of gravity to release the pawls when the friction is relieved by a rotation of the ratchet in a winding direction.

5. Hand brake mechanism comprising in combination, a rotatable ratchet adapted for connection to a winding device, a pair of pivoted and interconnected pawls located to engage the ratchet approximately at opposite ends of a diameter thereof to substantialy balance the load on the ratchet and hung for self-ratcheting action, one of the pawls having a first pair of rotarily spaced abutments, and rockable pawl actuating means having a second pair of rotarily spaced abutments located in the plane of rotation of the first abutments, the actuating means being freely rockable in one direction to permit the pawls to engage the ratchet and to contact an abutment thereof with a pawl abutment and in the opposite direction to contact the other abutments when further movement of the actuating means is resisted by friction between the pawls and ratchet teeth, the actuating means having a weighted portion causing further rotation thereof in said opposite direction under the action of gravity to release the pawls when the friction is relieved by a rotation of the ratchet in a winding direction.

6. Hand brake mechanism comprising 'in combination, a rotable ratchet adapted for connection to a winding device, a pivoted tension pawl and a pivoted compression pawl engageable with the ratchet to prevent unwinding of the device nection to a winding device, a pivoted tension pawl and a pivoted compression pawl located to engage the ratchet approximately at opposite ends of a diameter thereof to substantially balance the load on the ratchet and having toothed engagement with each other to interconnect the same, and means connected to one of the pawls for simultaneously moving the pawls into and out of engagement with the ratchet to respec tively prevent and permit release of the device.

8. Hand brake mechanism comprising in combination a rotatable ratchet adapted for connection to a braking device, a tension pawl, a compression pawl, and means for simultaneously moving the pawls into and out of engagement with the ratchet to respectively prevent and permit release of the device.

9. Hand brake mechanism comprising in combination, arotatableratchet adapted for connection to abraking device, a tension pawl, a compression pawl, the pawls being connected for simultaneous movement, and means connected to one of the pawls for simultaneously moving the pawls into and out of engagement with the ratchet to respectively prevent and permit release of the device.

10. Hand brake mechanism comprising in combination, a rotatable ratchet adapted for connec tion to a braking device, a tension pawl and a comn ul) thereof to substantially balance the load on the i I ratchet, the pawls being connected for simultaneous movement, and means connected to one of the pawls for simultaneously moving the pawls into and out of engagement with the ratchet to respectively prevent andpermit release of the device.

12. Hand brake mechanism comprising in combination, a rotatable ratchet adapted for connection to a braking device, a tension pawl and a compression pawl located on the same side of the ratchet axis and having cooperating integral formations whereby movementsof one pawl into and out of engagement with the ratchet effects like movements of the other. pawl, and means for actuating one of the pawls.

13. Hand brake mechanism comprising in combination, a rotatable ratchet adapted for connection to a braking device, a tension pawl and'a compression pawl located on the same side of the ratchet axis and hung for self-ratcheting action, the pawls having cooperating integral formations whereby movements of one pawl into and out of engagement with the ratchet effects like movements of the other pawl, and means for actu ating one of the pawls.

. EDWARD W. ZANE.

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