US3756161A

US3756161A - Draft controlled railway car spring arrangement

Info

Publication number: US3756161A
Application number: US00197442A
Authority: US
Inventors: H Loosli
Original assignee: Schweizerische Lokomotiv und Maschinenfabrik AG (SLM)
Current assignee: Schweizerische Lokomotiv und Maschinenfabrik AG (SLM)
Priority date: 1970-11-16
Filing date: 1971-11-10
Publication date: 1973-09-04
Anticipated expiration: 1990-09-04
Also published as: ES396674A1; CA943403A; AT317289B; BE775264A; CH531431A; SE374064B; FR2114429A5; GB1326310A; NL7017551A; NL140789B; IT941136B; ZA717049B; NO130388B

Abstract

Non-variable-rate springs are provided at some bearing areas while adjustable springs are provided at other bearing areas to uniformly maintain the loadings on the axles at the forward end at substantially equal values under a tractive effort. Control means are connected to the adjustable means to vary the force of the adjustable springs in response to the tractive effort of the power unit.

Description

United States Patent [1 1 (111 3,756,161

Loosli 51 Sept. 4, 1973 1 DRAFT CONTROLLED RAILWAY CAR [56] References Cited SPRING ARRANGEMENT UNITED STATES PATENTS [75] Inventor: Hugo Loosli, Winterthur, 3,429,454 2/1969 Glass et a1, 213/43 Switzerland 2,861,523 11/1958 Berry 3,548,755 12 1970 L' h 105 136X [73] Assignee: Schweizerische Lokomotiv-und C gg igg ffs fg wmteflhur Primary ExaminerGerald M. Forlenza Assistant Examiner l-loward Beltran [22] Filed: Nov. 10, 1971 Attorney l-lu gh A. Chapin and Francis C. Hand et a1.

[21] Appl. No.: 197,442

[57] ABSTRACT Non-variable-rate springs are provided at some bearing 30 F A l orelgn pplc auon pnomy Data areas while adjustable springs are provided at other NOV. 16, 1970 I Switzerland 16909/70 bearing areas to uniformly maintain the i g n the axles at the forward end at substantially equal values [52] Cl g ,25 374 under a tractive effort. Control means are connected to the adjustable means to vary the force of the adjustable [51] T Cl 861d 43/00 5/00 861g 9/00 springs in response to the tractive effort of the power Field of Search /73, 136, 215, unit 10 Claims, 5 Drawing Figures DRAFT CONTROLLED RAILWAY CAR SPRING ARRANGEMENT This invention relates to a rail motive power unit and particularly to a means for distributing the loading of the power unit on the axle supports thereof.

I-Ieretofore, rail motive power units, such as locomotives, have been known to have a vehicle body and at least three bearing areas distributed along the length of the vehicle body. These power units, particularly those having three or more bogies or individual axles have, however, had a problem in the distribution of the loading between the various axles. That is, in order to use the force of adhesion of the locomotive, all the axles, as a rule, have been driven and have required an appropriate loading. However, when the power unit exerts a tractive effort, the end to which the effort is applied becomes loaded while the opposite end (i.e.. the front end) is relieved of load. The problem is thus to ensure that the axles which experience extra loading do not apply an excessive axle loading to the rails and that the more lightly loaded axles are loaded equally so that optimum use is made of the adhesion force.

If the lightly loaded axles were loaded uniformly prior to application of the tractive effort, the reduction in loading for all the axles experiencing an individual reduction must be the same when the tractive effort is applied.

One known way of meeting these requirements is to divide a locomotive body in the center and to interconnect the two halves, e.g. by way of a swivel joint, so that the halves can rotate relative to one another around a transverse axis. Another known technique is for pairs of bogies to be joined together by a top frame which carries the vehicle body. Also, known are adjustable springing systems which use, for example, air springs in which requirements are set by means of appropriately adjusted controllers.

However, these known systems have been costly and have had a variety of disadvantages. For example, dividing of a vehicle body results in a reduction of rigidity and introduces the risk of the two parts or halves oscillating relative to one another in movement. Pneumatic suspension has been costly and requires a compressor to operate continuously, and possibly at ahigh level.

Accordingly, it is an object of this invention to provide a motive power unit in which the individual driving axles are loaded as required.

It is another object of the invention to load the individual driving axles of a motive power unit in dependence on tractive effort.

It is another object of the invention to provide an undivided rigid vehicle body having individual driving axles loaded in dependence on tractive effort.

It is another object of the invention to provide a relatively inexpensive means of loading the driving axles of a motive power unit.

Briefly, the invention provides a motive power unit having a body carried at at least three bearing areas along the length of the body with non-variable-rate springs at one or more bearing areas and adjustable springs at at least one other bearing area. In addition, a controller is connected to the adjustable springs to control the spring force thereof independence upon the tractive effort of the power unit.

In one embodiment, bogies are provided at each bearing area to carry the vehicle body while, in another embodiment, individual axles are mounted in a frame of the body at the bearing areas.

In another embodiment, the non-variable-rate springs are provided at the outer bearing areas while the adjustable springs are positioned at the inner bearing areas. In still another embodiment, the adjustable springs are positioned at the outer bearing areas while the non-variable-rate springs are at the inner bearing areas.

In operation, for example, where the adjustable springs are in the inner bearing areas and the nonvariable-rate springs are at the outer bearing areas, when a tractive effort is applied to one end of the motive power unit, e.g. the rear end, the forces of the adjustable springs are decreased so that the spring force of these springs equal the spring force of the nonvariable-rate springs at the opposite, i.e. forward, end of the power unit. In this way, the adhesion forces of the power unit can be effectively used. The relationship between the increase in tractive effort and the decrease in adjustable spring force can be proportional or non proportional.

These and other objects of the invention will become more apparent from the following detailed description and appended claims taken in conjunction with the accompanying drawings in which:

FIG. 1 diagrammatically illustrates a power unit utilizing a central adjustable spring according to the invention;

FIG. 2 diagrammatically illustrates a power unit having the adjustable springs at the outer bearing areas according to the invention;

FIG. 3 illustratesa view similar to FIG. 1 of a power unit having a reservoir for increasing the air spring volume of the central adjusting spring;

FIG. 4 graphically illustrates a proportional relationship between the tractive effort and the spring force of the adjustable spring; and

FIG. 5 graphically illustrates a non-proportional relationship between the tractive effort and the spring force of the adjustable spring.

Referring to FIG. 1, a locomotive includes a vehicle body 1 and three bogies I, II, III] at separate bearing areas along the length of the body 1 which supports the body 1. Each bogie comprises two driving axles 3 which are connected in known manner to traction motors 4 and which support the bodyl on suitable rails. The two outer bogies I, III have known steel springs 5 which are shown in diagrammatic form, whereas the center bogey II has air springs 6, only one of which is shown diagrammatically. The

springs

5, 6 are constructed in known manner so as to provide lateral stabilization of the vehicle body 1. The bogies I, II, III also have known elements, such as deep drawbars (not shown), which equalize the loading between the two axles 3 of each bogey.

The air spring 6 is connected to a compressor 7 via an air line 11 in which a check valve 8, a supply air reservoir 9 and a controller 10 are interposed.

The body 1 also includes a draw hook 12 where a tractive effort 2 is exerted as well as a pickoff 13 between the draw hook 12 and the controller 10 for measuring the the instantaneous tractive effort of the locotive effort Z measured. Alternatively, the motor current can be used as a yardstick for the tractive effort.

If the locomotive of FIG. 1 applies a tractive effort Z to the rails, since the tractive effort is exerted at the drawhook 12 some distance above the rails, the locomotive experiences a moment which increases the loading of the rear axlesi.e. the axles of the bogey III but decreases the loading of the bogies I, II. If the locomotive had merely identical types of steel spring with the same spring rates, the axle loading of bogey I would be reduced more than would the axle loading of bogey II, with the consequent risk of the wheels of bogey I slipping and appreciably reducing the tractive effort. For optimum tractive effort, the load reduction from the two bogies I, II must be uniformly distributed so that such bogies, and therefore their axles, are all loaded equally. Of course, the axles of bogey III experience an extra loading corresponding to the same total force as the amount by which the loading of bogies I, II is reduced.

To achieve this equal loading of the two bogies I, II, the controller 10 controls the force of spring 6 in de pendence upon the tractive effort, as shown in the diagram of FIG. 4. This diagram shows that the spring force P of air spring 6 decreases as the tractive effort Z increases, the decrease being so controlled by controller 10 that the spring force P is always the same as the spring force of the spring 5 of bogey I.

Clearly, the force P can be varied stepwise instead of steplessly. For instance, the spring force of spring 6 can, as shown by the curve b in FIG. 5, remain constant until the tractive effort Z reaches a critical value, then drop abruptly to the value for maximum tractive effort. A two-stage adjustment as indicated by curve in FIG. is another possibility, but it must be borne in mind in such cases that relationships are ideal only for a number of discrete values of tractive effort and are only approximately correct for other values.

Referring to FIG. 2, the locomotive can alternatively be provided with two sets of air springs in the bogies I, III. As in the previous embodiment, the air springs 20 shown represent a set of, as a rule, two air springs. These air springs 20 are connected via

air lines

21, 22 and control valves or

controllers

23, 24 to a compressor 25. As in the embodiment of FIG. 1, air reservoirs 26 are disposed before the

valves

23, 24, check valves are disposed between the reservoirs 26 and compressor 25 and the locomotive has a tractive-effort pickoff 13. The pickoff 13 is connected by

signal lines

27, 28 to the valves or

controllers

23, 24 respectively. The central bogey II has a set of constant-rate steel springs represented by a single spring 29.

In operation, when the tractive force Z originates and then increases, the forces in the two springs 20 change to ensure ideal alterations of axle loading with the

controllers

23, 24 providing independent control of the spring forces for each bogey I, III. That is, the spring force, i.e. the air pressure operative in each spring of bogies I, III, must increase asthe tractive effort increases.

As in the embodiment of FIG. 1, the conditions referred to, i.e. equal loading of the more lightly loaded bogies I, II, is achieved. If the springing is correctly chosen, the required load reduction can be achieved by the pressures in the springs of both bogies I, III varying in the same pattern, so that it is theoretically possible to use either a single controller or two identically operating and operated controllers.

In addition to obtaining bogey and axle load equalization when a tractive effort is applied, it is often necessary to prevent alteration of the selected loading of the bogies by track uneveness or changes in gradient, for instance, at a transition from the flat to an upgrade or a downgrade. To this end, referring to FIG. 3, an air reservoir 30 representative of an extra air volume is provided to provide this control. This reservoir 30 is connected into the line 11 to the air spring 6 and the operation thereof and of the controller 10 is similar to that described above in regard to the embodiment of FIG. 1. However, the increase in air spring volume due to the presence of the reservoir 30 leading to the spring 6 has a very flat rate, so that its spring force, i.e. the loading of the axles 3 of bogey II, varies little for vertical movements of bogey II.

The invention is, of course, similarly useful for motive power units having more than three bogies and/or individual axles. As a rule, extra controllers are necessary in such cases to control the extra air springs in the manner described.

The invention thus provides a motive power unit which has a relatively low initial cost and relatively low running cost compared to other systems using adjustable springing.

What is claimed is:

l. A rail vehicle motive power unit comprising a body;

at least three bogies for supporting said body along the length thereof;

a non-variable-rate spring disposed between at least one of said bogies and said body;

an adjustable spring disposed between at least one other of said bogies and said body;

a controller connected to said adjustable spring for controlling the spring force of said adjustable spring in dependence upon the tractive effort of said unit; and

means at one end of said body for measuring the amount of tractive effort applied thereat, said means being connected to said controller to emit a signal thereto in response to the measured amount of tractive effort for adjusting the spring force of said adjustable spring to obtain a substantially equal tractive force at said two bogies adjacent the opposite end of said body.

2. A rail motive power unit as set forth in claim 1 which further comprises at least two axles on each bogie.

3. A rail motive power unit as set forth in claim 1 wherein a non-variable-rate spring is mounted at each of the outer of said bogies.

4. A rail motive power unit as set forth in claim 1 wherein an adjustable spring is mounted at each of the outer of said bogies.

5. A rail motive power unit as set forth in claim 4 which further comprises a pair of said controllers each connected to one of said ajustable springs respectively and to said means to impart independent control.

6. A rail motive power unit as set forth in claim 1 wherein said controller is connected to said adjustable spring to decrease the spring force thereof in response to an increased tractive effort whereby the loading at all bogies as have their loading reduced by said tractive effort is reduced to the same extent.

7. A rail motive power unit as set forth in claim 6 further comprising an air reservoir connected between said controller and said adjustable spring for maintaining a substantially constant spring force in response to changes in vertical movements of said respective bogie.

8. A rail motive power unit as set forth in claim 1 further comprising means for maintaining a constant spring force in said adjustable spring in response to changes in gradient of said body.

9. A rail motive power unit as set forth in claim 1 wherein said means includes a draw hook at one end of said body for application of a tractive effort thereto;

a pick-off connected to said draw hook for measuring the amount of tractive effort applied thereto; and

a signal line connecting said pick off to said controller to emit said signal thereto.

10. A rail motive power unit comprising a body;

at least three bogies mounting said body thereon at three longitudinally spaced bearing areas;

a pair of said adjustable springs each mounted at the outer of said bearing areas between a respective bogie and said body;

an air reservoir connected to each adjustable spring to supply air thereto;

a pair of controllers each connected to a respective adjustable spring between said adjustable spring and a respective air reservoir;

a draw hook at one end of said body for application of a tractive effort thereto;

a pick-off connected to said draw hook for measuring the amount of tractive efitort applied thereto; and

a pair of signal lines each connecting said pick off to a respective controller to emit a signal thereto for adjustment of the spring force of said adjustable spring connected thereto, whereby said controllers increase the spring force of said adjustable springs in response to an increase in tractive effort to obtain a substantially equal force in said springs adjacent the opposite end of said body.

Claims

1. A rail vehicle motive power unit comprising a body; at least three bogies for supporting said body along the length thereof; a non-variable-rate spring disposed between at least one of said bogies and said body; an adjustable spring disposed between at least one other of said bogies and said body; a controller connected to said adjustable spring for controlling the spring force of said adjustable spring in dependence upon the tractive effort of said unit; and means at one end of said body for measuring the amount of tractive effort applied thereat, said means being connected to said controller to emit a signal thereto in response to the measured amount of tractive effort for adjusting the spring force of said adjustable spring to obtain a substantially equal tractive force at said two bogies adjacent the opposite end of said body.

9. A rail motive power unit as set forth in claim 1 wherein said means includes a draw hook at one end of said body for application of a tractive effort thereto; a pick-off connected to said draw hook for measuring the amount of tractive effort applied thereto; and a signal line connecting said pick off to said controller to emit said signal thereto.

10. A rail motive power unit comprising a body; at least three bogies mounting said body thereon at three longitudinally spaced bearing areas; a pair of said adjustable springs each mounted at the outer of said bearing areas between a respective bogie and said body; an air reservoir connected to each adjustable spring to supply air thereto; a pair of controllers each connected to a respective adjustable spring between said adjustable spring and a respective air reservoir; a draw hook at one end of said body for application of a tractive effort thereto; a pick-off connected to said draw hook for measuring the amount of tractive effort applied thereto; and a pair of siGnal lines each connecting said pick off to a respective controller to emit a signal thereto for adjustment of the spring force of said adjustable spring connected thereto, whereby said controllers increase the spring force of said adjustable springs in response to an increase in tractive effort to obtain a substantially equal force in said springs adjacent the opposite end of said body.