US2172848A - Hand brake mechanism - Google Patents

Description

Sept. l2, 1939. R. Q Q'CQNNOR 2,172,848

HAND BRAKE MECHANISM Original Filed Dec. 26, 1935 2 Sheets-Sheet 1 sept 12, 1939- R. c. o'coNNoR v 2,172,848

HAND BRAKE MECHANISM Original Filed Dec. 26, 1955 2 Sheets-Sheet 2 Patented Sept. 12, 1939 UNITED STATES-- PATENT OFFICE 2,172,848- HAND BRAKE MEGHANIsM Raymond C. OConnor, Chicago, lll'., vassignor to Union Railway.` Equipment Company, Chicago, Ill., a corporation of South Dakota Original application December 26,

1935, Serial No. 56,183. Dividedy and.- this application` April 22, 1937, Serial. l\1'o..138,358`

1 Claim.

pawl and ratchet mechanism and the hand wheelv for actuating the gear and winding drum.

Further objects and details will appear from a description of the invention in conjunction with the accompanying drawings, wherein- Figure 1 is a front elevation of the brakemechanism showing the hand wheel partly broken away;

Fig. 2 isa sectional elevation taken on line 2-2 of Fig. 1;

Fig. 3 is a detail ofthe pawl and ratchet mechanism taken on line 3 3 of Fig. 2, looking in thedirection of the arrow; and

Figs. 4, 5. and 6 are details showing the pawl and ratchet mechanism in different positions o-f operation.

The operating portions of the lbrake mechanism which includes the features of the presentv invention are enclosed within a frame comprising a front cover plate I6, a rear Wall II, end walls I2, and an arched over top wall I3. The end walls and top wall are formed integrally with the rear wall, and the front plate is secured thereto by rivets I4 or other suitable fastening means.

The front cover plate, as shown, is provided with an outwardly extending protuberance I5 in its lower portion, of arch shaped configuration, and in the center of said .protuberance the metal is outwardly bulged to afford a center boss I6 which receives the forward end of a gear wheel axle I I provided with a flanged head IB'which ts into a recess I9 formed in the inwardly protruding boss 2B on the rear wall I I of the frame.

The front end of the axle extends beyond the plane of the inner face of the protuberant lower portion of thefront plate and abuts against the inner face of the boss I6, being held in place by a Cotter pin 2l or other suitable fastening. The axle I'I is surrounded by a forward bushing 22, a rear bushing 23, and an intermediate bushing 24.

The forward and intermediate bushings are provided at their outer ends with flanges 25 which in conjunction abut against the ends of the hub 26 of a winding drum 2'I which is journaled upon the bushings. The forward bushing 22 abuts against a bridge plate 22a which spans the space across the protruding boss I6 and. has

itsA ends integrally formed with the end walls of theframe. This arrangement brings theforward-.and rear ends of the shaft I'I into direct alignment `with supports which are integrally formed in the frame, so that a very rigid and. rugged construction is provided and the shaft is accurately aligned within integrally formed portions-of the frame.

The winding drum is provided with a bifurcated web portion 28 furnishing a groove or channel 29 flanked on either side by the smooth cylindrical faces 30 of the periphery of the drum, which configuration affords a winding surface for the alternate links 3| of a brake chain, the intermediate links 32-1stand`1ngv in transverse relation andfin position to enter the center groove or channel 29 in the winding drum, so that as the chain is wound up, the alternate links will lie atwise. upon the drum surface with the intermediate links standing edgewise` within the groove.`

The bushing 23 furnishes the bearing for a gear wheel 33 having a web 34, 'a hub. 35, and a toothed rimV 36.V The web is provided at a suitable point with a forwardly projecting boss 3T provided with a bore 38 to receive a headed bolt 39V which extends through a hardened collar 40 which furnishes an anchorage for the terminalY link of thebrake chain, the anchorage being in alignment with the plane of the groove in the winding drum.

TheV above features of construction form the principal: subject matter of invention described and claimed4 in the application of which the present isa division, and it is not the intention to limit the use of the pawl and ratchet mechanism presently to be described to gears and drums of the vspecial character referred to or to any particular type of gear and drum arrangement.

The teeth of the gear wheel 33 mesh with pinion .teeth .Mon a hand wheel shaft'42, the forward portion 43 offwhich projects through an aperture 44 in the front cover plate I. The forward portion 43 of the shaft is squared and tapered and terminates in a threaded stem 45 entered through a square tapered bore 46 in the hub 4'I of a hand wheel 48. The hub as shown is inwardly elongated and provided with a square uniform bore in its center portion 49 to clear the surface of the square tapered portion of the shaft. The forward end of the hub, however, is provided with the square tapered bore 46 offset with respect to the uniform center bore and which aligns obliquely with a square tapered bore 5I at the inner end of the hub, so that these two terminal portions of the hub will come into wedging contact with the surface of the square unlformly tapered shaft 43, being held in clamped relation thereon by a nut 52 threaded on to the stem 45. The shaft 42 in advance of the gear teeth 4l is enlarged to afford a ratchet Wheel 53 having ratchet teeth 54 of saw-tooth formation. Between the ratchet wheel portion of the shaft and the square tapered portion, the shaft is cylindrically formed to afford a bearing surface 55 working within a bushing 56 which cooperates with a rear bushing 51 housed in a boss 58 in the rear wall to afford separated bearing surfaces for the hand wheel shaft.

The ratchet wheel 53 coacts with a pawl 59 having a tooth positioned to engage with the abrupt faces of the ratchet teeth, and a pawl is carried by a hub 6| provided with a center axial bore 62. The hub at its inner end is provided with an outwardly protruding segmental stop 63 extending throughV approximately 120, the ends of which furnish stops for engagement with the ends of a segment 64 formed on or rigidly secured to a coaxial handle shaft 65 upon which the pawl hub is pivotally mounted for limited rotation. The handle shaft at its forward end carries a handle 66 which extends beyond the cover plate and frame, as shown in Fig. 1, and terminates in a weighted' end Vportion 68. The hub 6| is provided with a counterweight 69, which assists in the release of the pawl tooth 60. The relationship of the handle shaft 65 with its segment 64 to the segmental stop 63 is one which permits the handle shaft to be turned freely through approximately before the end of the segment 64 abuts against the inner end of the pawl stop 63.

The bushing 55 is carried by a boss 10 formed in a plate 1| which is riveted to the end walls of the frame and stands in abutting relation to the inner face of the front cover plate when the parts are assembled.

With the pawl in engagement with the ratchet teeth as in Fig. 4, the weighted handle 66 will lie in a position below the horizontal, and the contact of the forward end of the segment 64 withV the upper end of the segmental stop 63 will serve to hold the pawl in engaged position As the handle is lifted and turned beyond its vertical position, as in Fig. 5, the rear end of the segment 64 will engage with the lower end of the segmental stop 63, and further movement will cause the disengaging of the pawl tooth from the ratchet wheel.

The rearward movement of the handle 66 is limited by a tooth 12 at the base of the handle which is adapted to abut against the stop 13 on the wall of the frame. The arrangement is one which permits the handle to be lifted freely upward and past the medial position without encountering any resistance, so that it is possible to effect a hammering action against the pawl segment 63, which may be highly desirable in cases where from freezing or other causes there is a tendency for the pawl tooth to lock with the ratchet wheel.

As shown in Fig. 6, after the pawl tooth has been carried clear of the ratchet teeth by the thrust of the handle 66, it will be swung further outwardly by the counterweight 69 until the pawl strikes the wall of the frame, which limits its outward movement. v The pawl is held in mesh with the ratchet in the on position by the weight of the release handle, and this arrangement enables a brakeman to force the pawl into engagement with the ratchet by pressing down on the handle in case the pawl should stick while in the off position. In releasing the brake, the handle is thrown about 40 past the vertical line, and in normal operations the operator will then turn the brake wheel sufficiently to take the strain off the pawl, which allows the handle to drop farther to the right and disengage the pawl from the ratchet. However, if diiculty is encountered in effecting the release, force may be applied to effect disengagement of the parts in the manner described.

The ratchet shaft with the pinion teeth thereon, as well as the pawl and pawl release handle, are journaled in the rear wall of the frame, and the front ends'are journaled in a plate secured to the frame in the manner described, so that With the parts thus assembled the working mechanism throughout will be accurately aligned and held -against displacement irrespective of the cover plate which simply performs the function of a closure for the frame and the working parts, which constitute a self-contained unit.

Although the invention has been described with particularty as to detail, it is not the intention, unless otherwise indicated, to limit the invention strictly 'to the mechanism in the form shown, since modifications therein may be made without departing from the spirit of the invention.

I claim:

In hand brake mechanism, the combination of a frame having an integrally formed rear wall and end walls with an upper bridge plate rigidly connected to the end walls and extending across the front of the frame between the end walls, a hand wheel shaft having its rear end journaled within the rear wall and its intermediate portion journaled within the upper bridge plate and extending forwardly therefrom, a toothed pinion rigidly secured to the hand wheel shaft, a ratchet wheel rigidly secured to the hand wheel shaft, a dog journaled within the upper portion of the frame between the rear wall and the upper bridge plate and an externally located handle for actuating the dog, a hand wheel rigidly secured to the forward portion of the hand wheel shaft externally of the frame, winding mechanism in train with the pinion, and a cover plate removably secured to the Vfront of the frame and overlying the upper bridge plate.

' RAYMOND C. OCONNOR.

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