US615141A - Hydraulic brake - Google Patents

Description

No. 6l5,l4!. Patented Nov. 29, I898. l .L. CLARK. HYDRAULIC BRAKE.

(Application filed. Oct. 11, 1897.)

3 Sheets-Sheet I.

(No Model.)

us ca, Pno'rouwo" A Nu. 6|5,l4|. Patented Nov. 29, I898. F. L. CLARK.

HYDRAULIC BRAKE.

(Application filed Oct. 11, 1897.)

3 Sheets-Sheet 2.

(No Model.)

WITNESSES: mvs TO M g M Att'y.

No. 6l5,'l4l. Patented Nov.'29, I898. F. L. CLARK;

HYDRAULIC BRAKE.

(Application filed Oct. 11, 1897.)

{No Modei.) 3 Sheets-Sheet 3.

UNITED STATES PATENT OFFICE.

FRANCIS L. CLARK, OF STEWART STATION, PENNSYLVANIA, ASSIGNOR TO THE CLARK BRAKE COMPANY, OF PITTSBURG, PENNSYLVANIA.

HYDRAULIC BRAKE.

SPECIFICATION forming part of Letters Patent No. 615,141, dated November 29, 1898.

Application filed October 11, 1897. Serial No. 654,844. (No model.)

To all whom it may concern: first to Figs. 1 and 2, I provide two brake-cyl- Be it known that I, FRANCIS L. CLARK, of inders 6 6, of smaller and larger dimensions, Stewart Station, in the county of Westniorerespectively, which are connected one to the land and State of Pennsylvania, have inother in line axially. The cylinder 6 is, as in- 55 vented a certain new and useful Improve- Patent No. 574,663 aforesaid, provided with ment in Hydraulic Brakes, of which improvea main piston 51 and a supplemental piston ment the following is a specification. 56 for the purpose of automatically and con- My present invention relates to and is an tinuously taking up wear and slackness or improvement in hydraulic-brake cylinders lost motion of the rubbing surfaces in the op- 60 [o and their accessories of the general charaO- eration of the apparatus, and, as in said patter of those set forth in Letters Patent of out, the main piston 51, which is of comparathe United States Nos. 574,663 and 574,665, tively short traverse, is fitted in a countergranted and issued to me under date of Janbore at the end of the cylinder to which liquary 5, 1897, which exemplify means for preuid is admitted, and its outward traverse in 65 [5 liminarily taking up the slack of the conneceffecting an application of the brakes is limtions and the clearances between the brakeited by a shoulder 53 at the inner end of the shoes and the wheels and subsequently apcounterbore. The supplemental piston 56, plying the brake-shoes to the wheels by the against which the piston-rod 16 bears, is, as action of separate and independent brakein said patent, fitted with suitable packing 7o cylinder pistons. in the smaller bore of the cylinder 6 beyond The object of my invention is to afford im-. the shoulder, and, as originally fitted, it abuts proved facilities for the performance of the against the main piston 51 and is moved by functions above stated with reliability and liquid subject to the pressure of said piston certainty under all conditions, as well as to 51 throughout the traverse of said piston in 75 minimize the power and quantity of liquidreeffecting an application of the brakes. A quired in the operation of the brake system helical spring 22, which bears against the and to properly and accurately adjust and head of the brake-cylinder through which the maintain the normal degree of clearance bepiston-rod passes, returns both the main and tween the brake-shoes and the wheels when supplemental pistons to their normal posi- 8o 0 the brakes are off. tions upon the release of pressure from the The improvement claimed is hereinafter main piston. fully set forth. In the construction set forth in Patent No.

In the accompanying drawings, Figure l is 574,663 a valvular mechanism was fitted in a View, partly in elevation and partly in secthe pistons 51 and 56 and the piston 51 was 85 5 tion, showing a brake-cylinder and controlprovided with a passage controlled by the ling-valve mechanism embodying my invenvalve of said mechanism for the admission tion; Fig. 2, a partial transverse section of liquid to the space between the pistons. through the brake-cylinder at the line mac of Under my present invention a material sim- Fig. 1; Fig. 3, a view similar to Fig. 1, illusplification is effected by wholly dispensing 9o trating a modification in structural detail; with an internal mechanism and substitut- Fig. 4, a partial transverse section through ing an external valve 65, which performs the the brake-cylinder at'the line y y of Fig. 3; functions of both the internal check-valve Figs. 5, 6, 7, and 8, partial longitudinal secand the independent hand-operated by-pass tions, on an enlarged scale, through the convalve of Patent No. 574,663. The valve 65, 5 5 trolling-valve and casing shownin Fig.3,illuswhich controls a passage 64, leading from the trating different positions of the valve; and larger bore of the cylinder 6, between the pis- Fig. SJ, a partial transverse section through tons 51 and 56, to the outer or supply side of the brake-cylinder at the line y y of Fig. 3, the piston 51, is fitted in a casing on the outillustrating a modification in the means for side of the cylinder 6 and is normally held to 100 unseating the releasing-valve. its seat by a spring 67. The stem 66 of the In the practice of my invention, referring valve is provided with a transverse pin to the valve-casing.

69, which is fitted to traverse, with the stem, in a recess in a removable cap 68, connected By unscrewing the cap slightly the bottom of the recess therein will abut against the pin 69 and unseat the valve.

A cylinder 6, of smaller bore than the cylinder 6, is connected to the outer end of the brake-cylinder 6 and closes said cylinder in the manner of a head, the cylinders 6 and 6 being fully open one to the other. A piston 51, which is formed integral with or otherwise fixed to the main piston 51 and is suitably packed, is fitted to traverse in the cylinder 6.

The supply and discharge of liquid to and from the cylinders 6 and 6 for the application and release, respectively, of the brakes is eifected bya valvular mechanism inclosed in a casing 10, the construction of which mechanism will now be described. The casing 10 communicates bya lateral branch pipe 5 with a delivery or pressure pipe which leads from a force-pump or other source of pressure, and the opening of the branch pipe in the casing communicates by a pipe 5 with the cylinder 6 on the outer side of the piston 51. The outer end of the cylinder 6, and consequently the space between the pistons 51 and 51, is connected with the casing by a pipe 5", and the casing 10 is connected by a pipe 5 controlled by an inwardly-opening check-valve 15, with a suction-pipe 5. The connection of the casing 40 and pipe 5 may either be a direct one or, as shown, through the intermediation of a liquid-storage reservoir 9. The pipe 5* is always open to the branch pressure-pipe 5 but communication between the pipes 5 and 5 is controlled by a check-valve 42, which is normally seated and opens toward the pipe 5, and also by a valve 41, which is connected to a piston -13, of larger diameter, and is held normally seated by a spring 44, bearing on said piston. The check-valve 12 also controls communication between the branch pressure-pipe 5 and the port in the casing, which is governed by the check-valve and which communicates with the branch suction-pipe 5. The three valves 41, 42, and 15 lift in the same directionthat is to say, toward the branch pressure-pipe 5.

The relation and manner of operation of the brake cylinder 6, pistons 51 and 56, and check-valve correspond in allessential particulars with those of the similarly-numbered cylinder and pistons and the check-valve 61 of Patent No. 571,663 and need not, therefore, be herein fully and at length described, it being only necessary to note that, as in said patent, liquid is admitted by the checkvalve 65 to the space between the pistons 51 and 56 and moves the piston 56 outwardly sufficiently far to take up the wear of the brake-shoes 011 the wheels, so as to maintain a uniform degree of clearance between the brake-shoes and the wheels. When the piston 56 has by increase of wear and slackness been advanced so far in the cylinder as to prevent it from making as long a stroke as that of the piston 51, the cap 68 of the casing of the valve 65 is partially unscrewed, and said valve is thereby unseated, and the liquid is released from the space between the pistons 51 and 56 until they are again brought in contact. Proper renewal or adjustment of the frictional surfaces and connections having been made, the further operation of the pistons is effected in preliminarily taking up slack, and therefore moving together for application, as in Patent No. 574,663. It will be observed that the valve 65 is not only more inexpensively applied and more conveniently located for insertion, removal, and replacement than the valve 61 of said patent, but also by its capacity of being manually unseated that it performs both the functions of said valve and of the independent by-pass valve 65 therein provided.

The operation of the valvular mechanism, which is inclosed in the casing 40, in the application and release of the brakes is as follows, it being understood that the space in the cylinders to the left of the piston 56 is full of liquid and that excess slack has been taken up, forcing the pistons 51 and 56 apart, so that they do not touch each other, but are held apart by the liquid between them: Liquid from the branch pressure-pipe 5 passes through the pipe 5 into the smaller cylinder 6 on the outer side of the piston 51 and forces said piston, together with the pistons 51 and 56, to the right, this preliminary movement of the piston serving to fully take up the slack and clearance of the brake-shoes, connections, and axle-boxes. In this movement the piston 51 acts as a pump, unseating the check-valve 45 and drawing liquid from the reservoir 9 or directly from the suction-pipe 5, as the case may be. \Vhen the brakeshoes '7 come in contact with the wheels 2 and the pressure of the liquid on the outer side of the smaller piston 51 rises sufficiently to overcome the pressure of the spring 1 1 on the piston 43, said liquid-pressure, acting on the dilferential area of the piston 13 above that of the connected valve 41, moves said piston to the right, thereby unseating the valve 41, and also closes communication with the reservoir 9 by seating the cheek-valve 4:5. The pressure from the branch pressure-pipe 5 is then exerted on the outer side of the piston 51. This piston being of materially larger diameter than the piston 51, a substantial increase of pressure is exerted, by which increased pressure the piston 51 is forced forward and applies the brakes with the maximum force desired, the additional action of the piston 51 being analogous to that which would be attained by an increase of leverage. lVhen the shoes are so worn that the piston 51 strikes the shoulder 53 before full application of the brakes, the liquid-pressure transmitted to the piston 56 through the passage 64t on the unseating of the valve 65 completes the application. In order to release the brakes, pressure is released in the pressure-pipe 5", and the spring 22 forces back the pistons 56 51 51. The liquid between the pistons 51 and 51 unseats the check-valve 42 and passes back to the pipes 5 and 5 As the pressure is released in the pipe 5 the spring 43 seats the valve 41. Liquid from the outer side of the piston 51 passes to the pipes 5 and 5 The modification illustrated in Figs. 3 and 4 difiers from that above described in the particular that the cylinder 6 is provided with a piston 51 which moves in opposite direction to the pistons 51 and 56, its relations to said pistons being similar to that of the piston 13 to the piston 15 in Patent No. 574,665. It also differs as to its controlling-valve mechanism, which is a modified and simplified form of that of said Patent No. 574,665. The brakecylinder 6, pistons 51 and 56, passage 64, and check-valve are similar in all essential particulars to the correspondingly-numbered members in the construction first described; but the smaller brake-cylinder 6 does not, as in the former instance, communicate with the larger brake-cylinder, but is separated therefrom by an interposed head 6", and the piston 51 of the smaller cylinder moves in 0pposite direction to the pistons 51 and 56 of the larger cylinder. A rod 14, which abuts against the piston 51, is coupled by a pin 14" to one end of a brake-lever 17, the opposite end of which is connected by a brake-rod 25 to the brake-beam (not shown) of one pair of wheels of the car. A rod 16, which abuts against the piston 56 of the larger cylinder, is coupled by a pin 16 to one end of a brakelever 17 the opposite end of which is connected by a brake-rod 25 to the brake-beam 26 of another pair of wheels of the car. The brake-levers 17 17 a are intermediately connected by a brake-rod 18. The supply and discharge of liquid to and from the brakecylinders 6 6 in the application and release, respectively, of the brakes are effected by a valvular mechanism inclosed in a casing 40, which communicates by a branch pipe 5, leading to a port in a valve-face in the casing, with a delivery or pressure pipe 5 which extends to a pump or other source of pressure and which may serve also for the release of pressure on the cessation of operation of the pump or the release of the pressure within it. A pipe 5 connects another port in the valveface of the casing with the larger brake-cylinder 6 between the head 6 thereof and the piston 51, and the pipe 5 is connected by a release-pipe 5, controlled by a release checkvalve 52, with the pressure-pipe 5". A pipe 5 leads from one end of the casing 40 to the smaller brake-cylinder 6 The valve-face ports of the pipes 5 and 5 are controlled by a slide-valve 47 ,which is provided with a port 47 and is connected to a stem 48, upon which is fixed a piston 50, which closes the end of the casing 40 opposite that to which the pipe 5 is connected, said piston abutting against a spring 51, contained in an extension 40 of the casing, the tension of which spring is adjustable by a set-screw 51 in the ordinary manner.

In the construction shown in Fig. 3 the ap paratus is assumed to be located on a trailercar, in which case only the pipe 5", connected with the pump, would be required. When used on a motor-car, the pipe 5 (shown in dotted lines) would be required to connect the pump to the reservoir containing the liquid. As in the instance first described, the brakecylinder spaces behind the pistons are supposed to be full of liquid and excess slack has been taken up, forcing the pistons 51 and 56 apart and interposing liquid between the pistons, which liquid is at all times subject to the pressure exerted by the spring 22. In effecting an application of the brakes liquid under pressure enters the valvecasing 40 from the pressure-pipe 5 through the port communicating with the branch pipe 5 and the port 47 of the slide-valve 47 (see Figs. 3 and 5) and passes from the casing through the pipe 5 to the smaller brake-cylinder 6, forcing out the piston 51 thereof, and thereby taking up the slack of the connections and bringing the brake-shoes against the wheels, as Well as moving the axle-boxes up to their bearings in the pedestals. The pressure exerted by the liquid on the piston 51 is transferred through the levers and connecting-rods to the brake-beams, and as the piston 56 and its push-rod l6 constitute the fulcrum or abutment at which the series of levers ends a force equal to that exerted by the liquid on the piston 51 will be transferred to the piston 56 and by it through the interposed liquid to the piston 51 and to the liquid on the left side thereof. This pressure per square inch will be as the relative areas of the two pistons. When the pressure in the valve-casing 40 exceeds the pressure of the spring 51 on the controlling-valve piston 50, the controllingvalve 47 is moved by said piston to the right until the ports are line and line, (see Fig. 6,) cutting off communication with the pressurepipe 5 and locking the liquid in the cylinder 6 and opening slightly the port to the cavity of the slide-valve 47 and from said cavity to the pipe 5 At this time the pressure from the pump in the pipe 5 holds the check-valve 52 closed against the pressure on the inner side of the piston 51 of the larger cylinder 6, said piston having been theretofore subjected to such pressure from the piston of the smaller cylinder through the lever-and-link connections between them. Liquid then passes from the pipe 5 through the recess or cavity of the valve 47 and the pipe 5 into the cylinder 6, moving the piston 51 thereof to the right, said piston, through the liquid interposed between it and the piston 56, also moving the piston 56 in the same direction. As soon as the pressure passes into the larger cylinder the direction of pressure is reversed and the piston of the smaller cylinder becomes the fulcrum, the pressure per square inch in the smaller cylinder rising in proportion to the relative transverse areas of the cylinders. This rise in pressure further compresses the spring 51 and forces the piston 50 of the controlling-valve to the end of its stroke to the right, fully opening the ports between the pipes 5 and 5, as shown in Fig. 7. The piston 56 moves faster than the piston 51 by reason of being of smaller diameter, and the traverse of the piston 51 is very short. If by reason of wear the piston 51 strikes the shoulder 53, liquid passes into the space between it and the piston 56 by unseating the check-valve 65. This movement of the pistons 51 and 56 applies the brakes with the desired degree of force, and the pressure reacts through the brake-levers and connections, the pin 11 acting as a fulcrum, and proportionately raises the pressure in the smaller cylinder 6. Upon the release of pressure in the pipe 5, which is effected only to such degree as not to discharge sufficient liquid from the cylinder 6 to permit the piston 51 to come to a bearing against the head 6, liquid passes from the cylinder 6 on the left side of the piston 51, unseating the checkvalve 52, and thereby releasing pressure from the inner side of the piston 51, and passes back through the release-pipe 5 to the pipe 5 the check-valve permitting its passage independently of the controlling-valve 47, the movement of which in regular sequence is not for this purpose essential. The instant that the pressure on the inner side of the piston 51 of the larger cylinder falls below that at which the controlling-valve was held in the position shown in Fig. 6 the piston 51 of the larger cylinder again becomes the fulcrum or abutment for that of the smaller cylinder, thereby slightly relieving the pressure in the smaller cylinder and valve-casing 40. The pistons 51 and 56 are moved inward by the spring 22, and the pressure on the piston 51 of the smaller cylinder is reduced to a point below the tension of the controllingvalve spring 51, which thereupon brings the controlling-valve 47 to the position shown in Fig. 8, slightly opening the port to the pipe 5 allowing a portion of the liquid to escape from the smaller cylinder 0 and relieving the pressure in said cylinder and in the valvecasing 40, when the spring forces the valve to the position shown in Figs. 3 and 5 and allows the liquid-pressure acting on the piston 51" to be released through the pipe 5 and the port 47 of the controlling-valve.

Instead of employing a connection between the stem of the valve 05 and the cap 08 of its casing as a means for manually unseating said valve by movement of the cap, as hereinbefore described, the same function may be performed by providing the cap 68 with an ordinary stnfling-box 70 and extending the valve-stem through the stuffing-box so as to be accessible to the direct application of the hand of the operator, as shown in Fig. 9.

Such construction I therefore specify as a substitute for that before described and for the purposes of my invention deem it a mechanical equivalent therefor.

I claim as my invention and desire to secure by Letters Patent- 1. In a brake apparatus, the combination, substantially as set forth, of a brake-cylinder, a fluid-supply pipe leading thereinto, a piston fitted on a counterbore at the supply end of said cylinder, a piston fitted to traverse in a smaller bore extending from the counterbore toward the opposite end of the cylinder, apiston-rod adapted to receive pressure from the smaller piston, a retract-ingspring bearing on said smaller piston, a passage leading from the supply-pipe to the space between the pistons, and a spring-seated valve seated in an external casing and controlling said passage, said valve operating automatically for admission and being adapted for manual operation for release.

2. In a brake apparatus, the combination, substantially as set forth, of a brake-cylinder, a fluid-supply pipe leading thereinto, a piston fitted in a counterbore at the supply end of said cylinder, a piston fitted to traverse in a smaller bore extending from the counterbore toward the opposite end of the cylinder, a piston-rod adapted to receive pressure from the smaller piston, a retractingspring bearing on said smaller piston, a passage leading from the supply-pipe to the space between the pistons, a spring-seated valve fitted in an external casing and controlling said passage, and a removable cap connected to said casing for manually unseating said valve.

3. In a brake apparatus, the combination,

piston, the supplemental piston being adapted to be moved by pressure imparted by the main piston through an interposed volume of liquid, a smaller brake-cylinder, a piston fitted therein, a brake-shoe, connections through which pressure on the pistons is imparted to the brake-shoe, a passage from a source of fluid-pressure supply to the smaller cylinder, a valvular mechanism, actuated by oppositely-exerted fluid and spring pressures, through which valvular mechanism and passages controlled thereby, fluid under pressure is delivered from a supply and release pipe to the main piston of the larger cylinder and to the space between the main and supplemental pistons of the larger cylinder, and a release check-valve controlling communication between the fluid supply and release pipe and the larger cylinder.

4. In a brake apparatus, the combination, substantially as set forth, of two brake-cylinders of different diameters, a main piston fitted in a counterbore at the supply end of the larger cylinder, a supplemental piston fitted to traverse in a smaller bore extending from the counterbore toward the opposite IIO IIS

end of the larger cylinder, a passage leading from the supply end of the larger cylinder to the space between the pistons thereof, a spring-seated valve controlling said passage, a piston fitted to traverse in the smaller cylinder, a brake-shoe, connections through which fluid-pressure on the pistons is imparted to the brake-shoe, a passage from a source of fluid-pressure supply to the smaller cylinder, through which fluid is primarily supplied to the piston of the smaller cylinder, to take up the clearance and slack of the brake connections and impart initial pressure of the brake-shoe to a wheel, a valvular mechanism actuated by oppositely-exerted fluid and spring pressures, through which valvular mechanism and passages controlled thereby fluid is supplied to the larger cylinder to effeet the application of the brake-shoe with determined greater final force by a comparatively short traverse of the pistons of the larger cylinder, and a release check-valve controlling communication between a fluid supply and release pipe and the larger cylinder.

5. In a brake apparatus, the combination, substantially as set forth, of a larger brakecylinder, having a main and a supplemental piston,the supplemental piston being adapted to be moved by pressure imparted by the main piston through an interposed volume of liquid, a smaller brake-cylinder communicating with the larger cylinder, a piston fitting said smaller cylinder and fixed to the main piston of the larger cylinder, a brake-shoe, connections through which pressure on the pistons is imparted to the brake-shoe, a passage from a source of fluid-supply to the smaller cylinder, a Valvular mechanism, actuated by oppositely-exerted fluid and spring pressures,

through which valvular mechanism and passages controlled thereby, fluid is supplied to the main piston of the larger cylinder, and a release check-valve controlling communication between a fluid supply and release pipe and the larger cylinder.

6. In a brake apparatus, the combination, substantially as set forth, of a larger and a smaller brake-cylinder, pistons fitting said cylinders, a brake-shoe, connections through which pressure on the pistons is imparted to the brake-shoe, a pipe for the supply and release of fluid under pressure, a valve controlling communication between said pipe and the larger cylinder, a piston connected to said valve, and subject to the pressure in the fluid supply and release pipe, a spring acting on said piston in direction opposite to that of the action of pressure thereon, and a release check-valve controlling a communication between the larger cylinder and the fluid supply and release pipe.

7. In a brake apparatus, the combination,

substantially as set forth, of a larger and a smaller brake-cylinder, pistons fitting said cylinders, a brake-shoe, connections through which pressure on the pistons is imparted to the brake-shoe, a valve-casing having connections to a pipe for the supply and release of fluid under pressure, and to the larger brake-cylinder,a controlling-valve traversing in said casing and adapted to establish comcontrolling a communication between the larger cylinder and the fluid supply and re=- lease pipe.

FRANCIS L. CLARK.

Witnesses:

J. SNOWDEN BELL, WALTER L. MERWnv,

' munication between the larger cylinder and

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