US1462270A - Automatic slack adjuster for brakes - Google Patents

Description

Jilly 17, 1923.

' A. R. K. DJURSON AUTOMATIC SLACK ADJUSTER FOR BRAKES Filed April 27. 1921 Patented July 17,1923.

FATE

owner..

AXEL BUDOLF KONRAD DJURSON, OF MALT/IO, SVEDEN, ASSIGNOR' '10 SVENSKA .AKTIEBOLAGET BROMSREG'ULATOR, OF STOCKHOLM, SWEDEN, 'A COMPANY.

AUTOMATIC SLACK ADJUSTER FOR BRAKES.

Application filed-April 27, 1921. Serial No. 464,864.

T 0 all whom it may concern Be it known that I, AXEL RUDo r Kon- RAD DJURSON, a citizen of Sweden, residing at Malmo, in the county of Malmohus, Sweden, have invented certain new and useful Improvements in Automatic Slack Adjusters for Brakes, of which the following is a specification.

My invention relates to automatic slackadjusters for brakes of the type shown for example in Patent No. 128363 1, November 5,

1918, in which a feeding deviceis arranged in the brake mechanisnn which feeding de vice acts upon a turnbuckle or other suitable take-up device for. reducing. the play, the feeding device being connected with a yielding member which, when friction arising in the mechanism by the increasing brake pressure stops further movement of the same, absorbs the rest of the movement of the feeding device during the braking operation. Devices of this kind are already known.

The continual transmission of the'movement of the brake mechanism to the slackadjuster is, however, affected with several disadvantages, which are removed by the present invention. i

' As taking-up of the slack always must be done at the cost of a certain increase of the stroke of the piston of the brake cylinders or a corresponding member and it is very important that this increase is as small as possible, it is of course very desirable that the period during which takingup of the slack takes place causes the smallest possible increase of the stroke, which increase in slack-adjusters of the kind mentioned above hitherto used always is proportional to the size of the slack to be taken up.

Besides, the movement of the driving member acting upon the slack-adjuster ought to be limited as much as possible in order.

to prevent that the yielding member of the slack-adjuster will be too much strained.

Finally, the slack adjuster ought to return toits starting position as soon as possible when loosening the brake, so that it has time to reach this position, before the piston or corresponding member has returned to its starting position, because the springs or the like, wh ch bring the sa e back to i s start:

ing-position, oftenly do not function satisfactorily but allow the piston in the brakecylinder to stop before this position is reached. Then if it should happen that the slack-adjuster has not returned to its start ing-positionbefore the piston has finished its return movement the slack-adjuster will begin to work with the new position of the piston as starting-position, which means increased slack.

Moreover, as the piston rod only'exceptionally is provided with parallel guides the mechanism of the slack-adjuster will always be influenced by and dependent on thp1 eventual side movements of the piston ro These disadvantages are removed by the present invention by giving the slack-adjuster a discontinual movement differine from and independent of the movements of the piston rod orv the corresponding memher as well in longitudinal direction as lat-- erally. These lateral movements of the piston rod are incident to the play of the piston or rod due to looseness where the rod is not eXteriorly guidedf V p In the accompanying drawing Fig. 1 is a side view of the slack-adjusting mechanism according to the invention and Fig. 2 is an end elevation thereof.

The numeral 1 designates the brake cylinder, 2 is the brake piston, 3 the piston rod and 1 the spring that brings the piston back to its starting position. The levers 5, 6 are in the usual way connected with the brake cylinder 1 and the piston rod 3 and connected with each other by means of the rod 7. At the ends most remote from the brake cylinder said levers are connected with the brake rods 8, 9 leading to the brake blocks. The conventional slackndiuster 10 is placed on one of theserods 9. On theouter end of the piston rod or on some other suitable part of the brake mechanism roller 11 is provided, said roller running lna slot 12' rod 15 are guided by the member 13 and are connected with each other by means of a link or the like 17. The guide 13 is pivotally connected with some part 01. the truck by means of a rod 18 and a pin 19 insuch a. way that itis prevented from moving in the longitudinal direction but allowed to take part in the lateral loose play movements of the piston rod. The longer the rod 18 in relation to the distance between the rolers 11 and 1 1, the more the influence of the lateral movements of the piston rod on the crank 16 is reduced.

The slot 12 in the guide 13 is not straight but provided with an oblique part 20 arranged in such a relation to the crank 16 on the slaclcadjuster that when the roller 14 on the end of the connecting rod 15 passes through the same at the movement of the brake piston 2 the slack-adjuster will be acted upon for taking up an eventual too large slack. By giving the link 17 a suitable length, so that the roller 14.- is placed at a distance from the oblique part 20 of the slot 12 corresponding to the desired slack, the extent of the slack may easily be predetermined.

The operation of the device described is as follows. lVhen brali'ingtakes place the brake piston is moved and also the roller 14 in direction towards the oblique part 20 of the slot 12. When this movement has proceeded so far as to correspond to the predetermined slack the roller 14 has reached the oblique part of the slot, and at further movement the connecting" rod 15 will be moved upwards whereat he crank 16 of the slack-adjuster is turned If the slack should happen to be greater than the predetermined slack a screwing together of the slack adjuster takes place and thus also a reduction of the slack. 011 the contrary, if the slack is normal the brake blocks will rest against the wheels at the same moment as the roller 1 1- arrives to the oblique part 20 of the slot in the guide, whereat strain arises in the brake mechanism and thus also in the slack-adjuster 10, so that the friction in the latter in a known way prevents the same "from turning in relation to the rod 9 and thus stops a further taking up of the slack. In this case the continued turning of the crank is taken up by the yielding member in the slack-adjuster.

By increasing the angle formed by the oblique part 20 in relation to the rest of the slot 12 a large movement of the crank 16 in relation to the movement of the brake piston is obtained, which as shown above is important for obtaining a stroke as constant as possible.

As the roller 14- when the broke is loosened is forced to follow the slanting slot 20 the slack-adjuster returns to its starting-position before the brake piston, whereby is ensured that it does not have any effect upon the operation of the slack-adjuster, it the brake piston, as often is the case, should not completely return.

By limiting the inclined part 20 of the slot in the guide an unnecessary .overstrain of the yieldin member in the slaclcadjuster is excluded.

Further it is evident that the influence of the eventual lateral movements of the piston rod will be eliminated which is of a great importance, especially as the piston rod often is not guided.

The new invention has also the advantage that the slack may be determined before, hand easily and correctly.

Having described my invention, What I claim is 1. An air brake controller having; a piston rod, a slack adjuster, a member for operating the slack adjuster, a guide formed with a slot slidably receiving 'a connection from said member and a connection from said piston rod, said guide being movably mounted to respond to loose play of the piston rod, said guide being formed to positively operate said member in a predetermined movement of the piston rod.

2. An air brake controller having a piston rod, a slack adjuster, a member for operating; the slack adjuster, a guide formed with a slot slidably receiving a connection from said member and a connection from said piston rod, means joining said connections, said guide being movably mounted to respond to loose play of the piston rod, said guide being formed to positively operate said member in a predetermined movement of the piston rod.

3. An air brake controller having a piston rod, a slack adjuster, a member for operating the slack adjuster, a guide formed with a slot slidably receiving a connection from said member and a connection from said piston rod, means joining said connections, said guide being movablv mounted to respond to loose play of the piston rod, said slot having an inclined portion positively operate said member for slack adjustment in a predetermined movement of the piston rod.

4. An air brake controller having a piston rod, a slack adjuster, a member for operating the slack adjuster, a guide formed with a slot slidably receiving a connection from from said member and a connection from said piston rod, means joining Sk -id connections, said guide being movably mounted to respond to loose play of the piston rod, said slot having a straight portion normally receiving the piston rod connection and member connection and an in In testimony whereof, I have signed my name to this specifioation in the presence 10 of two subscribing Witnesses.

AXEL RUDOLF KONRAD DJURSON.

1 Witnesses: r

ERNST PERSON, G. Pn'rnnsson.

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