US2475111A - Wheel chock - Google Patents

Description

A. c. RIIIDLAND I WHEEL OHOCK Filed July 22, 1946 2 Sheets-Sheet l v @fEIIEIIIZEIeZ E- f' Jaw/5.272 771" Juan der 5!: az-lesflz'dlazvi July 5, 1949. v 'A. c. RIDLAND 2,475,111

vmm. cnocx Filed July 22, 1946 2 Sheets-Sheet 2 Patented July 5, 1949 UNITED STATES PATENT OFFICE 23 Claims.

This invention is concerned with a wheel chocking device for temporarily blocking vehicle wheels against rolling. A primary object of my invention is to produce a sturdy and effective wheel chock which can be folded into a relatively compact form when not in use. My invention further provides a mechanism which is light in weight and easy to manipulate, and which operates reliably when used on rough ground as well as on a smooth surface. At the same time my wheel chock has a structural simplicity well adapted for economical manufacture. All of these characteristics make it particularly well adapted for use with light aeroplanes, but my invention is not limited to this particular application.

Further objects and advantages of my invention and a full understanding of its nature will be appreciated from the following description of an illustrative preferred embodiment and of certain modifications thereof. This description is to be read in conjunction with the attached drawings, of which:

Fig. 1 is an elevation of an illustrative wheel chock, according to my invention, in position under a wheel;

Fig. 2 is a similar elevation of the chock in its folded position ready for stowing;

Fig. 3 is a partially cut-away plan view of the chock in its folded position;

Fig. 4 is a perspective sketch of the device in operating position;

Fig. 5 shows a fragmentary plan View, similar to Fig. 3 but including only one end portion, showing an alternative manner of constructing the chock members;

Fig. 6 is a fragmentary perspective, showing a second alternative form of the chock members;

Fig. 7 is a side elevation of a modified form of my chocking device, in position under a wheel;

Fig. 8 is a side elevation similar to Fig; 7, but showing the device in its folded position;

Fig. 9 is a partially cut-away plan view, corresponding to Fig. 8;

Fig. 10 is a transverse section of the folded device taken on line l0--l0 of Fig. 9;

Fig. 11 is a perspective view of the modified wheel chock in operating position; and

Fig. 12 is an enlarged fragmentary section on line i2--l2 of Fig. 9, showing preferred structure of friction treads on the chock plates.

My wheel chocking device comprises primarily an extensible frame 12 including chock carriers I6, supporting chocks 20 which are adapted to engage the periphery of the wheel I0 to be checked. The chock carriers [6 are urged toward each other by suitable tension means, maintaining the chocks in firm contact with the wheel. To facilitate stowing when not in use, chocks 20 are hinged or pivoted to chock carriers l6 and are releasably locked in their operating position (Figs. 1 and 4) by the braces 25.

In the embodiment illustrated in Figs. 1 to 4 chocks 20 are formed of single pieces of tubing, bent as indicated in the drawings, with a concave curve on their swinging ends, giving surfaces at 2| adapted to engage the rubber tire of an airplane wheel. The tube ends are flattened at 23 and drilled to form pivot bearings. Chock carriers l6 are also single pieces of tubing, formed by a single sharp right angle bend or angle at 11 into an L-shape, of which one leg l6a constitutes the chock pivot pin. The chock is restrained axially upon pivot IBa by any suitable means such as the cotter pins Ill. The other leg 16b of each L-shaped chock carrier l6 enters an end of guide tube l3, which thus serves to join the two chock carriers and to guide their relative motion. This motion of chock carriers I 6 and their carried chocks 20 is of two types: unrestricted rotation relative to tube 13 and to each other about the tube axis; and axial sliding motion within tube 13, limited and controlled as described below. Central guide tube l3 and chock carriers It thus flexibly linked to it comprise the essential structure of the extensible frame [2 mentioned above. It ,will be obvious, however, that the entire structure illustrated can be modified in many respects without departing from the scope of my invention.

Chock braces 25 are shown as simple rods, their upper ends 25a bent at right angles and pivoted in holes 26 in chocks 2D; and their lower ends 25b similarly bent and slidingly pivoted in the slots 21 cut through the walls of tubular legs l6b of chock carriers l6. Within tubes Hib the two brace ends 251) are connected to each other by spring 30 and also (preferably) by a flexible cable 31, both of which are preferably, but not necessarily, anchored midway of their lengths to the transverse pin 32 centrally placed in guide tube 13. Due to the general symmetry of the device, the two functions performed by spring 38 of urging brace end 25b and chock carrier it toward guide tube 13 will be performed in much the same manner whether spring 30 is anchored to tube l3 or not.

Spring 30 urges the sliding motion of brace ends 25b in slots 21 in the direction toward slot ends 21a; and also, once the brace contacts the slot end, urges the inward sliding motion of chock carriers It in guide tube I 3. While the described structure thus permits the single spring 30 to perform two distinct functions satisfactorily, this does not prevent the use of separate spring means, if desired to urge chock carriers l6 together independently of the motion of the chock braces. Inward motion of the chock carriers is limited by contact of the end of tube [3 with brace end 2519 Where it enters-slot 21;; andis limited outwardly by cable 3!; which. isnormally slack; but which is short enough to prevent leg I61) of chock carrier Hi from being removed completely from guide tube 13. If the outward motion of chockbarriers 29 is suitably limited by other means, cable 3! can of course be omitted.

Sliding motion of brace end 25b in slot 21 .in the direction toward slot endZlaraises 'chock'2fl to its operating position (Figs. 1 and 4) whi1ermotion in the opposite direction lowers it to its fold- .-,.ed. position- (Figs. 2..and 3). .The. end 21a of slot This solocated, that it stops the spring urged sliding motionof brace .2 i-whenl the latter is approximately .vertical -and hence-when the chock isvfullyfraised. Since,the1.directionof brace .25 r isthen nearly normalrto slot. 2l ,..whatever thrust the braceis ,requiredtp: transmit from chock. 26 to chock; carrier-J fi can'havepnly asmall-compo- --nent-;parall el to the; slot. .=-10nly m oderate tension :ofspringrttis therefore required tohold the brace firmly rin, chocle supporting position against :the end-Elwoftheslot. ably so -placed,thatbrace525 .isislightly-past vertical', asrindicated in'j-Eig; 1. -.,-Downward;thrust .onthe brace then tendslio holdit more tightly against the slot ,end,.-. minimizing thezdanger. of

the brace-being accidentally-displaced from'its chock; supporting position.

The slot end 210,115 prefer- 2=The wheeleng-aging-isurface 2|:1of:the chock is .on.the swinging: endxof the-chock,- :and; when the -device:- is; in, use,this-.:.surface.- lies? generally. .be-

tween v,wheel axis llxand chockraxisfl :andclose such factors as friction Land: the: size shape. and

structure. OfUthBEWhBG]. .tire. .-.Accordingly, my 1 wheel chock: is "preferably'so constructed that" the chockingelem'entsfw in s'operatingt position pro-. jectixabove the;.plane. Zdefined :-.by.".wheel axis J! l and chock. axis '32 2.:3at- .such: an. angle that the resultant: thrust: of the wheel :upon i'ChOCk surface 2 I will bezidi-rected capproximately toward richock axis 22. The: thrust. :then :has. a'.relativelyx-ilarge componentr'in 'the'ipIaneLof;thelchock, and a relatively. small .compohentt;perpendicular. t. 1 this plane. The larger-component is transmitted through the :chock. axi's toi the ground; and i only the smallerxzompcnen'tissupportedbyibrace.25.

Accordingly; choekrbrace' fi serves primarily to hold chock 20 in its chockingpositi'on; and-does not itself sustainthemain; thrust-.rofi the;'cho'cked fwheel .10.

:of: the :exact typexforqwhich a igiveni'chocking' .de-*

This:is:tr.ue; ideallwonly for a wheel vice is specifically designed. However, there is no need for the condition described to be satisfied accurately, and in practice a chocking device of given size can effectively accommodate a consid- 5 erable range of wheel sizes. Transmission of the wheel thrust through the chock to the ground may be via carriers l6 which may be provided with ground engaging means; but is preferably through the chocks themselves, which, for this 10 purpose, may have sharp cornered square ends.

In the folded positionof Figs. Z'and 3 the chocks and their braces 25 lie substantially in the nsame plane, and spring 30 holds brace ends 25%; against the ends of tube i3. In this folded posi- "tion the spring thus has no tendency to raise the :chocks. To :raise the chocks and prepare the device for. use it is only necessary to lift the checks toward the position of Fig. 1 and to pull them outward. F This may be conveniently done by grasping the chocks at 2!; and pulling up and out. ;.-Dl) lil1g tl1at, operationbrace endszb will remain .efigainst-the ends-of-tube cl3 as carriers I I6 slide .outwarddn. tubeqlS until-tha-slotends 210, are pulled .outegainst brace'ends .-25b and the chocks 5 areifully raised. v-Further :ou-tward movement of the checks andcarriersis then opposedby spring 68. 'Separation of chockoarriersi l Bis continued, distending-springfiil;until cable 3i becomes taut or until the. clearanceybetween the upper. extremes :,of ,thetwcnchocks-lfl is sufficient,:.to'-:receive the wheel slllheldevicesis thenuinserted beneath "wheel 56,:andr5pring 30-;is:a'llowed to=.draw.chock carriers ".5 fictogetheruuntil :chocksi .Eiltengage the I ..:periphery of ithewheel. izSpringa'dll firmly-maintains thisrengagementg andatithe same time holds brace ends 25b in contact with slot ends 2111, effectively .lo cking; therbraces shock I support- .ing position. iiltqmay-benoted that if the wheel to. be chockedeisztoo, large .toallow :the procedure 0 .just. described;-.the sdevice may-Jstillbe used by :slidingcit into positionmwith chock carriers l6 .zfully. separated, but with'chocks126 held fiat as in Fig. 2 until after they are underthe wheel.)

:The .cho'c'king device :can: be. withdrawn-from :under. the wheel. by first separating chock carriers it against the force of spring iifi. f The de- ....vice isithentfolded' by. simply telesco'pingchock carriers It togetheritvithinrguide tube-"l3. When the ends'ofthis tube-contactbra'ce ends 25b, still in the position showm-iIi -Fig 1 these are forced to :slide ialong islets- 27, automatically folding chocks 20, and completing the-preparation for istowing.

Sin'ce the device-as"illustrated-in Figs. 1 to 4 is 55. symmetrical with respectto" the plane of base frame [2 (in its normal position); itis-immate- "rial; to which side or: this 'plane chocks 2 0 swing whenthey-are unfdlded;- so'longas both swingto "the same s'ide. Thiscanyof course, be arranged readily by slightmanu'alpressure upon the chocks -as chockccarriers ilfi are iirst drawn apart. The symmetry referred tois not necessary to my invention; 'an'c'l'canbe modified: to suit special requirements. For example, .inthe particular em- .65 -bodiment here illustrated; :the' two-corners 230.

and 23b of the fiattened chock tube ends 23 can be shaped differently: to suit idifferent types of ground. :The cho'cks. can then be swung to one side or the "other 'of baseztrame l2 to bring the --desired formation at -23-into use.

As has already been noted; the chock carrierswith 'theirlchocks. are E freeto rotate about i'theaxis of guide tubel3. P-his rotation'offers :the great;advantage of allowing "the two chock 'carriersito" assume different angles when used on rough ground, thus conforming to the surface and rendering the chocking action more positive and reliable than if the entire structure were rigid.

Although the device has been described as including, and preferably does include, two oppositely disposed chocks and carriers, a single chock device which is in substance one-half of the described two-chock device may be used for some purposes. Such a single chock device would embody substantially those parts which are shown in say the left-hand half of Fig. 3, with the spring so in this case necessarily anchored at its righthand end to tube l3.

The chocks can of course be formed in many ways other than that illustrated in Figs. 1 to 4. For example, as illustrated in Fig. 5, they may retain their general tubular form but be pivotally mounted on chock carriers It by means of tube sections 4!] which fit over the carrier arms lfia and act as pivot bearings. A second alternative form of chock, illustrated in Fig. 6, consists of a single sheet metal stamping 45, which may have appropriate strengthening flanges 46 and channels ll and a flanged wheel contacting surface Such a stamping can include a sleeve forma ticn as indicated at 49 to act as a pivot bearing for carrier arm lea. I do not intend that these particular forms of chock construction illustrated be construed as a limitation of the scope of my invention.

When my chocking device is used on a smooth surface such as a concrete floor, particularly if it is used with a wheel of relatively small diameter, the wheel may have a tendency to slide the chock over the floor. This is because the direction of thrust of the wheel against the chock makes a relatively small angle with the surface of the floor, giving a relatively large horizontal component and a relatively small vertical frictionproducing component. This tendency can be reduced by the use of chock plates, such as are included in the modification of my invention illustrated in Figs. 7 to 12. Besides the use of chock plates, this modification illustrates how one chock carrier can act as frame member to support the other, eliminating the central frame member I3 of Figs. 1 to 4.

The fundamental structure and operation of this modification are the same as in that already described. However, the coaxial tubular legs of the chock carriers 56 and 51 are longer than before and are of different diameter sothat one can slide within the other. The telescoping motion of one tube within the other is limited inwardly by contact of the end of each tube with the end 652; of the check supporting brace 65 associated with the opposite carrier; and outwardly by any suitable means such as cable 68 connecting the two brace ends. The tension spring 69, attached to the two brace ends, urges them together, and also urges together the two chock carriers when the braces are in contact with the inner ends 61a of slots 61. The operation of chock supporting braces 65 to raise and lower the chock members 66 is the same as in the first described modification, with the slight distinction already mentioned that each brace end is pushed outward as the device is folded by the end of the opposite chock carrier rather than by the end of a central guide tube.

This form of my device, besides eliminating the central guide tube, allows somewhat greater longitudinal flexibility of the device, thus allowing it to embrace a larger wheel or fold to a more compact size or both. It will be evident that with 6 this form there is no need of centrally anchoring spring 69 and cable 68.

The chock plates 15 are shown in Figs. '7 to 12 as steel Dressings. These are essentially fiat but have strengthening flanges it along their sides and friction ridges 71 on their upper faces. These ridges can be formed, as shown in Fig. 12, like the well-known louvre openings such as are frequently used to provide ventilation. Chock plates 15 are secured to the remainder of the structure only at their outer ends which are pivoted to the upper ends of chocks 66 for rotation about axes parallel to those of the chock pivots 56a and 51a. Preferably the pivot axes of the chock plates are formed simply by extensions of the upper ends 65a of chock supporting braces 65, as shown most clearly in Fig. 9.

In operating position under the wheel chock plates it are supported at their upper ends by these pivots, and their lower ends rest directly on the ground, as shown in Fig. 7. They are so proportioned that as the wheel starts to roll the tire presses downward on the lower part of the chock plate. The direction of this thrust being nearly vertical, it creates a strong frictional resistance to slipping at its surface of contact with the ground. This prevents the entire device from sliding. The main thrust of the wheel is transmitted from the upper portion of the chock plate through pivot 65a to the check itself and, as before, longitudinally through the chock to the ground.

When the device in its present form is folded the projecting ears Bl welded to the sides of chock plates 15 contact the upper surface of the chock carriers and force the plates to rotate about pivots 6504 into the plane of chocks 66, as shown in Fig. 8. The plates are prevented from turning beyond this position by contact with stops i8 welded to the cross members Sta of the checks. Thus when folded, the position of the plates is restricted by stops 18 on the one hand and ears 8! on the other, insuring a compact form of the entire device. As the chock carriers 55 and 51 are telescoped together one chock plate partially nests inside the other. To facilitate this nesting one plate is made slightly wider than the other, as can be seen clearly in Fig. 9, and one of the ears 8! is preferably attached to its plate in a slightly higher position than the other, as is shown in Fig. 8. Ears 8! are preferably so located on the chock plates that in operating position they are well clear of the chock carriers, as in Fig. 7, so that the swinging ends of the plates are supported only by contact with the ground or floor.

Various other changes and modifications may be made from the illustrative designs which have been described without departing from my invention, the scope of which is defined in the following claims. In these claims I use the term telescopic, with relation to frame member l3 and carrier in, or with relation to two carrier members such as 56 and 51', to denote capability of relative extensive and contractive movement, whether or not one member slides with relation to the other, or, if it slides, whether or not the two members are relatively sliding tubes. For instance, it is suflicient to the described functioning of my device that the chock carriers be movable in contractive and extensive relation to the member called the frame or with relation to each other. And if that movement is one of sliding, the sliding association of the frame and carrier 75 maybe of any suitable formation, although a aetsn 1 1 tubular formationis preferable for simplicity-and for the flexibility which has been noted? When one chock carrieris related directly "to the other without any intervening" frame= member each carrier is to be construed as forming a frame for theother. Andl may also-note-that, if-atubular or similar sliding formation is usedit is immaterial whether the --frame tubeor tliecarrier tube is the external one.

I claim:

1. In a device for checking a wheel; two-chock carriers telescopically relatedfor longitudinal relative motion between relatively contracted-and extended positions and also=forrelative swivelling movement about a longitudinal ax-la a--cho'ck swingably mounted on eachcarrientd swing about a transverse chock axis betWe'en'a -folde'd position essentially ina longitudinal plane-and an operating position-projecting abovethat plane, and chock holding members eachassociatedwith a chock and the corresponding carrier' and adapted to hold the check in its operating "position.-

25A device as defined in claim-'1, and-alsoim cluding a frame member extending longitudi nally between the twochock carriers and-telescopically andswivelly related to each'carrie'r.

3. In a-device for shocking a wheel"; two chock carrierstelescopically related for longitudinal relative motion between relatively contracted and extended positions, a chock swingably =m'ounted on each carrier to swing about a transverse chock axis between a folded positionessentiallydn a longitudinal plane and an operating position in'a plane projecting upward -from the-long-itudinal plane, and means acting betweeneachchock and its corresponding carrier to support'th chock in its operating position.

4. ma device for chocking a-wheek-two chock carriers telescopically related for I longitudinal relative motion betweenrelatively contracted-and extended positions, a chock mounted on each carrier for swingingmoveinent about a transverse axis thereon between a folded positione-ssentially in-a longitudinal plane and an operating position in a plane projecting upward frorn the'longi tndina-l plane and inward "fromthe said'axls, and means for releasably supporting checks in their operating positions.

In' a device for chock-ing-awheelftwo 'chock carriers telescopically related for longitudinal relative motion between relatively contracted and extended positions, chocks movably mounted on the carriers for motion relative thereto into "and out of operating positions, means "for releasably confining the chocks in their operating positions; said means being movable into and'out' of-chock confining positions, and means associated "with the chock confiningmeans and adaptedto move the confining. means tochock confining'position by .virtue of motion of the chock carriers toward their relatively extended positions.

6. In adevice for chockinga wheeLtwo chock carriers telescopically related for.=longitudinal relative motio-nibetween relatively contracted and extended positions, chocks movably 'mounted on the carriers for motionrelative thereto into and out of operating positions, means for. zreleasably confining .the checks intheir' operating positions, said meansbeing movable into and :out of chock confining positions, and means associated :with therchock confining means and .lwithlzthe carriers andadapted 'Jzto' move the: carriers *out ofxtheir chockl' confining positions by virtue of inbtlon of the carrierstoward their relatively contracted positions.

'7. In a device forchocking a wheel, two chock carriers telescopically related for longitudinal relative' motion betweenrelatively contracted and extended-positions, chocks movably mounted on thecar-riers for-motionrelative thereto into and out 0f operating positions, means for releasably confining the chocks in their operating positions,

saidmeans beingmovable into'and out of chock confining-positions;spring meanstending to move the -chock-confining means into their chock confining positions-andimeans for moving the chock confining means out of their chock confining positions by virtue of motion of the chock carriers toward their relatively contracted positions.

8. In a' device for chocking a wheel, two' chock carriers telescopically related for longitudinal relative motion between relatively contracted-and extended positions, chocks movably mounted on the carriers for motion relative thereto into and out of operating positions, means forrelea'sably confining the chocks in theiroperating positions, said means being movable" into and out of chock confining positions; and unitary spring means tending to "move said chock confiningmeans into theifchockconfining positions and tomove'the chock carrierstoward their relatively contracted positions.

9.111 a device for checking a Wheel,a "frame member, a chock carrier telescopically-relatedto the frame member for longitudinal relative motion between relativelypontracted and extended positions, a choc'kswingably mounted on'th car- "riento swing about a transverse chock'axis beextended 1 positions 10."In"a device for checking a wheeLa frame member, a chock carrier telescopically related to the-frame member for longitudinal relative motion between-relatively contracted and extended positions, a chock swingably mounted -on the carrier to swing about a transverse chock axis between 'a iolded position essentially in 0. longitudi =nal-planeandi'an operating position projecting above-that *planareleasable means for holding the check in'a its operating position with relation 'to-= the a carrier; saidmeans movable between chock-holding .and chocl -'.releasingpositions, and means associatediwith the frame member-and the chockLholding means and-tending to move the holding means to its chock-releasing i position-- by virtue of inovementof the carrier toward itscontracted position.

1t. cThelideviceidefined in claim 9 and in which sthexlas't-imenti'oned :means comprises a tie member connected between the holding means-and the frameamember: l

12.?Thedevice defined -in1claim 9 and in which the lastzmen-tioned inea-nscomprises an extensible spring tie member connectedbetween the holding meanszandtheaframemember.

13.' The' deVi'ce' defined in claim '10, and also inclziding means associated-with the frame member and 'thei -lchock holdi'ng means and -tending to movethe-hol'ding means to its chock holding posi- 9 tion by virtue of movement of the carrier toward its extended position.

Id. In a device for chocking a wheel, a frame member, a chock carrier capable of longitudinal motion relative to the frame member, a chock mounted on the chock carrier and rotatable about a transverse axis between a folded position essentially in a plane through said axis and parallel to said longitudinal motion and an operating position projecting out of that plane, a brace pivoted on the chock and slidably pivoted on the chock carrier for longitudinal sliding motion, a stop limiting the said sliding motion at a point at which the brace is at an angle to the direction of said sliding motion and supports the chock in its operating position, and spring means tending to move the brace toward the stop.

15. In a device for chocking a wheel, a frame member, a chock carrier capable of longitudinal motion relative to the frame member between a relatively extended position and a relatively telescoped position, a chock mounted on the chock carrier and rotatable about a transverse axis between a folded position essentially in a plane through said axis and parallel to said longitudinal motion and an operating position projecting out of said plane, a brace pivoted on the chock and slidably pivoted on the chock carrier for longitudinal sliding motion, a stop limiting the said sliding motion in a direction toward the frame number at a point at which the brace is at an angle to the direction of said sliding motion and supports the chock in its operating position, spring means tending to cause motion of the brace toward the stop, and a surface on the frame member adapted to contact the brace and to cause sliding motion of the brace away from the stop when the chock carrier approaches its said telescoped position on the frame member...

16. A chocking device as defined in claim 15, and in which the spring means comprises a spring attached at one end to the sliding end of the brace and effectively attached at the other end to the frame member, so that the spring tends to move the carrier toward its telescoped position when said end of the brace is against the stop.

17. A chocking device as defined in claim 15,

and in which the frame member is in the form of a tube, and the chock carrier in the form of a telescopically related tube, the spring means bea tension spring lying within the two tubes and attached at one end to the sliding end of the brace and effectively attached at the other end to the frame tube, and the end of the frame tube constituting the surface on the frame adapted to contact the brace.

18. In a device for chocking a wheel, a frame tube, a chock carrier tube adapted for longitudinal telescopic movement with relation to an end of the frame tube, a transverse axis member carried by the carrier tube, a chock swingable about said axis member between a position substantially in the plane of the tubes and the axis member a position projecting from that plane, the carrier tube having a slot through its wall extending from a slot closed end outwardly away from the end of the frame tube, a chock brace pivotally connected at one end to the chock and having its other end extending through said slot for pivotal and sliding movement therein, and a spring located within the tubes and effectively connected to the sliding end of the brace tending to move that end of the brace toward the closed end of the slot.

19,. In a device for chocking a wheel, a frame 10 tube, a chock carriertube adapted for longitudinal telescopic movement with relation to an end of the frame tube, a transverse axis member carried by the carrier tube, a chock swingable about said axis member between a position substantially in the plane of the tubes and the axis member and a position projecting from that plane, the carrier tube having a slot through its wall extending from a slot closed end outwardly away from the end of the frame tube, a chock brace pivotally connected at one end to the chock and having its other end extending through said slot for. pivotal and sliding movement therein, and a spring located within the tubes and effectively connected to the frame tube and the sliding end of the brace tending to move that end of the brace toward the closed end of the slot, and tending to move the carrier tube toward the frame tube when the brace contacts the slot end.

20. In a device for checking a wheel, a frame member having two longitudinally opposite ends, two chock carriers telescopically related respectively to the two frame ends, and adapted to move longitudinally inwardly and outwardly with relation thereto between contracted and extended positions, a chock mounted on each carrier for swinging movement about a transverse axis thereon between a position essentially in a longitudinal plane and a position projecting from that plane, a brace pivoted to each chock and pivoted slidably to the respective carrier to have 10ngitudinal sliding movement with relation to the carrier, each carrier having a stop which limits the inward sliding movement of the associated brace to a position in which the brace is at an angle to its directions of sliding movement on the carrier, and spring means acting effectively between the sliding ends of the two braces tending to move them toward each other.

21. In a device for chocking a wheel, a ground engaging frame, two chocks mounted on the frame in longitudinally spaced relation and swingable about transverse chock axes between folded positions essentially in a longitudinal plane and operating positions projecting above that plane, the line of intersection of the planes of the two chocks in said operating positions lying above the said longitudinal plane, ground engaging chock plates mounted on the swinging ends of the checks for pivotal movement about axes essentially parallel to the said chock axes, said chock plates having ground engaging sur faces at their swinging ends and being swingable between folded positions essentially in the planes of the chocks and operating positions at such an angle that the line of intersection of the planes of the chock plates lies below the said longitudinal plane, and means for releasably supporting the chocks in their operating positions.

22. In a device for chocking a wheel, a generally iiat frame, a generally flat chock pivotally mounted on the frame for swinging motion about a pivot axis which lies substantially in the plane of the frame and in the plane of the chock, the chock carrying a wheel engaging surface generally transverse of the chock plane on one side of the said axis, and carrying two alternative ground engaging formations on the other side of the said axis and oppositely disposed with respect to the plane of the chock, said chock being swingable about the said axis between two operating positions substantially symmetrically disposed on opposite sides of the frame, and releasable means for confining the chock selectively in either of the said operating positions.

gaging.v chock plateswmonntedeon the swingin l0 ends of. the checks ion pivutaLmovement, about axes essentially pafalleljozthe said. ichock. axes, said chock, pl-atesahavingt round eng8igil1g1 surfaces attheir swinging .endstand being. swingable between -o1ded positions. .essentiallydnlthe planes of the checks and operating nosltionsat such an angle. that the line:ofiintersdti'onmiLthe planes .12 of. the .chock, plates eliesrbelowthevsaid longitudinal plane,'the swinging ends o. the.chock plates inntheiri operating positions being supported only by ltheinground engagement... andmeans for vre- Ieasably, supportingthe .chocks in their operating positions.

. ALEXANDER CHARLES RIDLAND.

" REFERENCES :CIIED :The following references are-of record in the file-:of thie-patent:

UNITED STATES PATENTS Nummr .Name Date 15 1,216,430 Smith .wmum.-- .Aug.. 20, 1918 2,184,487 Clark Dem-26, ,1939

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