US2149203A - Cushioning mechanism - Google Patents

Description

Feb. 28, 1939. E. H. BLATTNER CUSHIONING MECHANISM 2 Sheets-Sheet -1 Filed Jan 3, 1935 Fe 1939- E. H. BLATTNER CUSHIONING' MECHANISM Filed Jan. 3, 1935 2 Sheets-Sheet 2 Patented Feb. 28, 1939 PATENT" OFFICE CUSHIO-NING MECHANISM Applicationmlanuary ll, 1935, Serial -No. 281

16' Claims.

This-invention :relates to railway idraft rigging; I and, .more particularly, to cushioning, mechanism-- associated therewith and allowing fora greater travelpof'the couplerunder buff than :under draft,

eiawith the ..coupler.movement being resisted f-by a greater. shock absorbing capacity than is interposed against draft-movement.

The :principal object of my invention, generally considered, isthe provision of a double end draft' lo 'gear or cushioning mechanism'adapted forseriesapplication to provide a. greater bufiing than draft: energy absorbing capacity,-,with:.the. body portionpthereof slotted for. receiving. a draftkey for connection with associatedrsills.

Another. object of my, inventionpis to provide shock-absorbing: mechanism comprising a body casting and a cushioning unit ateach end thereof, each unit comprising friction shoes,,associatedresilientmeans; and a central wedge mem- ,-,,ber. for urging. thefriction ,shoes together, the elements :of;each cushioning-unitbeing held assembled-by alongitudinally extending bolt,= with ahead at each'end; which bolt is,adaptedfor being locked. in. place bya-turning;90' about its 3 axis after. insertion.

slotted body portion. spacing helical spring barrelsdisposed atthe ends,-1seats being providedfor .:,the;.ends:of'said2springbarrels and cooperating friction" and. wedge' elements enclosed: in each: barrel, and certain of. said elements; engaging:

the interior :thereof, the. seats and:.enc1osed ,elee

mentslqbeingr locked; together against? relative 351. turningr movement," the wedge; elements beingconnected to the body portion by bolts preferably formednwith'; integral heads.

Other :obj ects and advantages :of: the invention.

relating to: the particular 'arran'gement'and 3 conparent .aspthe description: proceeds:

Referring to the drawings. illustrating; my in.

vention, thepscope whereofis definediby the ap.

pended claims one form of my" cushioning vmechanism shown assembled" with associated". draftgrigging,

Fig. 21is-a transversee sectional view of the.

. cushioning mechanism on'the line 2-2 ofFig. 1,

looking in the direction of "the arrows.

Fig.3 is a partial end elevational view of the body; member; of the cushioning mechanism, shownpartly'insection on the line- 3-.3rof' Fig. 1,

2 looking; in zthe direction of; the arrows.

Aestill further'object of "my invention'is -theprovisiontof cushioning mechanism comprising a structionzof the various parts"willrbecome apof :the slots =6 being extended rearwardly of the Figureil' is'a partial. side elevational view and" partial vertical longitudinal '1 sectional. View of.

Fig. 4 is an end elevational View of the cushion-v ingmechanism with the associated follower removed.

Fig. 5 is an-end elevational view of one of the outer segmental shoes removed. from'the mechanism;

Fig. 6. is a side elevational viewof the shoe shown in Fig. 5. I

Fig. 7; is a'fragmentary side elevational view of one of theretaining bolts.

Fig. 8.is an end view. of the-bolt shown in Fig. 7, looking from the left.

Fig. 9 is. an end view of the bolt shown in Fig. 7 looking from the right.

Fig. 10 is a. partial side elevation and partial vertical longitudinal sectional view 'of a modified form of cushioning mechanism involving my invention.

Fig. 11..is a fragmentary sectional view on the line- I Ill of Fig. l0, looking in-thedirection of the arrows.

Fig. 12;.-is,;a fragmentary sectional view on the line l2-'l2- of Fig. 10, lookingin the direction ofthe arrows.

Referring to'the drawings in detail, like parts beingdesignated by like referencecharacters, and first considering th'e embodiment of my invention illustrated in Figs.- 1 to 9, inclusive, there is shownone embodiment of my double-ended series friction draft gear I, said gear preferably comprising a body member-or casting 2,- and a-helical spring. barrel 3ldisposed at either end thereof. The bodymember or casting 2 is slotted, as indicated atl; for receiving a ,draft key orother stop: means 5; whichextends through slots 6 inv cheek plates (not shown) connected to associated draft sills (not shown), and holds the body memher 2 against movement under-:the-action of draft forces, while permitting rearward movement under the action of bufling forces, onaccount normal position, of the key 5; The gear or cushioning mechanism I may have a front follower 1; a rearfollower. 8, and bedisposed betweenthe. arms and rear portion of a horizontal yoke :9: and acoupler: In, said yoke being. connectedxto said coupler I0 in any usual or desired manner. The yoke normally engages a backstop H.

Each helical springbarrel 3iis desirably formed ofstockrectangular orzsquare in section; has a plane cylindrical inner surface, and reacts between an outer spring plate oraseat' l2. and an inner springplate or seat 13; Inasmuch as the spring barrels .3:. and: associatedymechanism are.

identical at both ends of the body 2, the mechanism at one end only will be described. The face of each seat I3, away from a spring 3, engages outstanding flanges l4 on a set of segmental friction elements or shoes I5, preferably two for each seat, which shoes frictionally engage the inner surface of the barrel 3, and the inner ends of which engagethe body member 2 of the mechanism.

A complementary set of inner segmental friction elements or shoes l6 bear against the inner faces of the shoes l5, which faces, and the engaging surfaces of the shoes I6, are desirably generally cylindrical and have corresponding curvatures, but are normally slightly inclined to the longitudinal axis of the mechanism, and are provided at their outer ends with outstanding flanges I! which overlap portions of the outer seat I2. A central thrust element or wedging member l8, normally seating on the follower 1 or 3, as the case may be, projects inwardly at each end of the gear and is provided with faces I9, inclined to the longitudinal axis of the mechanism, cooperating with complementary wedging faces 20 on the shoes l6. The wedge member 3 is laterally elongated in cross section, and extends substan tially across the chamber of the barrel 3, interfitting between the segments of the shoes I 5 and It.

The seats l2 and I3 are generally annular in form, and the outer seat I2 is recessed, as indicated at 2|, to receive the flanges ll of the friction shoes l6 and prevent relative axial rotation therebetween. The body member 2 is provided with outstanding lugs 22 which fit in corresponding notches 23in the flanges M of the shoes I5, thereby interlocking said shoes against rotation as the springs 3 unwind and rewind during compression and release of the gear. The body member 2 also has outstanding central bosses 24 around which fit the shoes I 5. The lateral extensions 25 of the central wedge member iii are disposed between adjacent side portions of the shoes l5 and I6, and prevent rotation of said wedge member with respect thereto.

In order to hold the parts of the mechanism assembled and Emit outward movement of the central wedges i8 with respect to the body member 2, I connect each Wedge I8 to said body member by means of a longitudinally extending bolt 25. Each bolt has a preferably integral head 21 at its outer end, and a preferably integral head 28 at its inner end. The head 28 is desirably elongated laterally, as shown most clearly in Fig. 9,

and the apertures 29 in the central wedge member i8 and the corresponding apertures 30 in the body member 2 are correspondingly elongated horizontally, for example, in the embodiment illustrated, as shown most clearly in Figs. 2 and 3.

The bolts 26 may be applied for locking the parts together by inserting the head 28 of each through the apertures 25 and 30, when the head is disposed horizontally, and after said head has passed through the corresponding aperture 3! turning it about the axis of the bolt to a vertical position, or that illustrated in Figs. 1, 2 and 3, when the bolt will be locked against removal by having the end portions of its head 28 received in pockets or notches 3! extending upwardly and downwardly from the aperture 30. Undesired turning of the head 28 is positively prevented when the bolt 25 is under tension, because of the relatively snug'fit of the head portions in the pockets 3|.

Release of the head from the aperture 3B is, of course, effected, by movement of the corresponding wedge l8 toward the bodyv member 2 until the ends of the head are released from the pockets 3|, then turning the head until it registers with the apertures 30, and removing the wedge and bolt,

The surface 82 of the head, which is adjacent the key 5, is desirably concavely curved to correspond with the curvature of the adjacent or edge portion of the key, so as to increase the engaging area where said bolt would pound against the key during operation of the gear, and provide bifurcations lying on either side of the edge portions of said key. The head 2? is too large to pass through the aperture 29, and may be formed of some desirable shape for receiving a wrench or other means for turning the bolt to looking or unlocking position, as desired.

From the foregoing description, it will be seen that I may employ the mechanism described to provide differential action for cushioning draft and bufling forces. Under the action of draft forces, the body member 2 is held stationary by the key 5, which also limits inward movement of the bolts 26 during compression of the gear, and the coupler Hi pulls the yoke 9 forwardly through its connecting means (not shown), moving the rear follower 8 and pushing the rear wedge l8 and associated friction shoes !6 into the rear friction shoes 15, compressing the rear spring housing 3, and thereby actuating only the rear cushioning mechanism or rear half of the double-ended gear I, utilizing only one half of the total capacity of said gear 1, and at the same time permitting only one half of the movement permitted upon a full compression of said gear.

Under the action of buffing forces, however, the butt of the coupler H2 engages the front follower 1, pushing it and the associated friction wedge l8 and shoes l6 into the front shoes l5, compressing the front spring housing 3, and simultaneously moving the body casting 2 rearwardly so that the rear friction mechanism is simultaneously and similarly actuated and compressed, so that a full compression of the entire mechanism I is effected. On account of this action under buff, not only is an increased energy absorbing capacity provided, but a coupler travel is permitted equal to the sum of the travels permitted by the friction elements at each end of the gear. Although, for convenience and economy in manufacture, the gear is desirably made symmetrical so that the travel and capacity provided by each end is substantially identical, yet this is not essential in accordance with the broad aspect of my invention, and the capacities and travels of the two ends of the gear may be equal or different, as desired.

Although I have disclosed a manner of operating my double-ended gear so that a less amount of cushioning effect is provided for draft forces than for bufiing forces, it will be understood that I do not Wish to be limited to this use of said gear, as it may be used as an ordinary single-ended gear. It will also be noted that, if desired, I mas use the gear so that a greater amount of draft capacity is provided than bufiing capacity, by arranging the associated rigging and harnessing the gear between the associated sills of a railway vehicle in a manner such, for example, as de-- scribed and claimed in the Barrows application I wallsa 35abeing preferably the normally? vertical; In? order to hold the parts 'ofi the mechanism walls, and the Walls 36 and 31 bein'g lrespectively; to'pvand bottomxwalls .althoughiit wilbbeiunderstood thatslaamiinot'nlimitedivtoeusingsthe gear'im' thiszpositio'rt. Thevwallsifit 3firamic3t' are con:- n'ectedvandabracedz transversely by walls138 pref erablyi extending: from: the": en'ds or connecting? websror flanges 3.9.v Saidiwebsrorflanges-3972mm the; corresponding; ortionse ofithe side walls: 351' areiprovided:withalongitudinalislots lb 'forrreceiv ing'a; draftt key; (not showm)? ors'otheri-meansi for: connectingthez-liousingrortcushioning -mechanismi to associated: cheelcl'plateszandiorr drait sillsflnoti shown-)2 1 T'het: cushioning mechanism;v H involvesi two sets of: associated wedges; or shoess and: resilient; means onerset: clisposedi forwardly oh the front partitiomtai and: the other disposed: 'rearwardly-i- V ofithe?rearipartitionaaiiic Betweenthe tworpartw 20 tionsilz and i outwardiyi 'thereot; the walls: of? the housing, M as we'l-lflasi sai'dzl partitions; are desirably? aperturedii as indicated atAOeA tandfliuto faciiie tate core removal andassembiy ofithe'partsa housingzzisz provlded witlr aacompartment or pocket 43i inieach end; the forwardicompartnrentl being dispesediforwardior:the rfront panti tiom38g: and; thezrearfcompartmentlbeing disposed rearward-' of the rear partition 38 said compartments are desirablwdefiiredfia theirtouter edges: by flangZas or Web's 44 partially closing; openings into I said compartrnent's and pref erablyr extending-i from the extreme :ed'g'es ofi the sidewalls- 3 6 and: 32: adjoining thecorrespor'idl'rigportions: off the" walls-235i Tne'seiflangesiprovideupper andfilowen pocketsm 5 111 theimaini compartmentsilfl receive ingu per-r and lower resilient: means: 481 which desirablyi'tahe the formioiisetsioi': curved plate springs. Associatediwith: acnlsetrofispringszis" a" Wear pl'ati 415- th'e' end portions of: which are desirably notchedior slottedi asindicatedt at'14'8pto receive corresponding nibs 49 whi'ch causeather 7 individual 1: plates: to bei interlo'ckedzwith respect to one anothe'rand 'said we'ar"plateltherebm pre I ventin'g undesired lateral shiitingztherebetween in a manner such as described I and: claimed the" suckow eatent'iNoz'. l;884,913;.iof-I October- 25; 19321 Associated with: each set" of springs 46 is a friction shoe'ror Wedge memben: It! formed: with airiction' ,7 surface 2t! engaging: a' correspondingz friction' surface I9 on arcenter wedge or 'spreader niember- 'l8 '.-1 Each central wed'germember" I8 desirably h'as an outer portion- SO -'eicteHded lateF ally-to fiinction' as -a foll'ower ror enga'gement with gga-drawb'ar or 'yok'e; as the caseimayrbei Ii'i ordr tb faeili'taite release of -the mechanism as well"'as' increasethecapacity of t e' g ea'rg -the center Wedges or plungers l 8 and'the associated friction shoes or wedges: la -are formed holiowmoor; provided with pockets receiving release-springs 3 *which1-in' the preser'i-t embodiment; take the form'of relatively long coilsa Saidrele'ase springsact at their iiiner sends onthetran'sverse par ti tions 3'8" and" are centered about projection's"-oi*-' tlugs 5l out'standing therefrom The -outer erids of said springs act onannular flanged portions fl of the wedge rnembers l 8 0'11 account of 'using release spring's', itis not' necessary toi make-the wedges-bluntenough to -be" self releasing.-

: In orderto provide renewable wearing sur faces'gon the transverse" partition 38; friction plates 53 are desirablyapplied over the outer =sur-'--- facesof said partiti'ons for "engagement by the wedges I 6 and the adjacentf ends of the curved npiate -sp assembled and limit outwardlmovement of the central Wedges I81 witlr'respect to':'tlie housing. 2 I'iconne'ct each wedge [8 to said housing.- member b'ymeans oiiia longitudinally extending bolt 26". Each bolt has a preferably integral head 21* at its' 'outer end and a preferab'lyintegral head 28' at its iniier end; The:'head:a28 '-is' desirably elongated-i laterally; a's sho'wmmost clearly? in" Figure 1 2; and the: apertures i9 in the central" wedge m'ember E8 "'andwthe corresponding apertures 30 im the housing: member 2" are correspondingly elongated horizontall-yglfor: example, in "the embodiment illustrated; as: shown" most clearly in Figsr-nli and 1 2;

The bolts ZB may'be applied for locking thepartstogether' by "inserting-the head 28 of each through theregistering apertures 29 and 30 when =th'e1head is disposedihorizontally; and after said head ha's passed -through the: corresponding apei' tui'e w fturning it"aboutthe' axis of-the bolt to 'a verticalpositiongrwhen the bolt will belocked against removalvby having the end portions of it's'z hea'd 28 "re'ceivediin-pockets or notches 3| extending? upwardly and 'downwardlyi from the aperture 30 Undesired turning-ofthe head 28 is :p'o'sitively prevented when the bolt 26 is under tension: because of the relatively snugfit of the" head portions in the pockets 3!. Releaseof the head from the: aperture 30 is, of'course, effected in th'e -same manner-as that'of thehead 28- of the'embodimentof Figsul to 9, inclusivea The lie'aels fl and ifi 'may beiorm'ed-as the headsZT and: 28 sot the: first embodiment, or as illustrated. It will also-be understood that the mechanism of the present embodiment may be usedlike the mechanismof said'first embodiment.

Although--preferred embodiments of my invention have beenillustrated, it will be understood thatmodiiicationsmay be madewithin the spirit and scope of the appended claims.

I claima H Cushioningmechanism comprising a housing with -a' pocket'defined by longitudinal and otherwall's, .friction blocks movable laterally in saidpocket awedge block with a taperedportion' fitting between said friction blocks, resilient meansdisposed between said friction blocks and said longitudinal walls, anda bolt for limiting movement of said wedge block' away from said friction blocks, said bolt' having ahead at each end; one of 'said heads being elongated, 'and'said housing. and wedge block having elongated slots for receiving said elongated head; said housing havin'gia' bolthead pocket angularly disposed to saidliousing'slot toffor'iri a'receptacle for said elongated bolt" head; said bolt being locked in place after insertion by turning approximately abou its"axis;' toth'ereby position said e1ongated bolth'ead"in s'aidb'olt hea'd pocket.

2 C'iishioni'n'g mechanism comprising a body member" with a transverse draft-key-receiving slot, cushioning mechanisms comprising a helical spring barrel 'di'spose'dhteach" end of said memberfa seatforeach'endof each spring; c00perat-' key, when in place, prevents displacement thereof from operative positions.

3. Cushioning mechanism comprising a body portion formed with a transverse aperture for receiving a connecting draft key, and a helical spring barrel disposed at each end thereof, a seat for each end of each spring, cooperating segmental friction shoes arranged in pairs, the members of each pair being anchored to said seats respectively disposed adjacent said body portion and at opposite ends of the mechanism, a central wedge member at each end of the body portion and acting between said friction shoes for urging them outwardly into engagement with one another, said central members being in wedging engagement with the inner friction shoes, and bolts for holding the parts of the mechanism assembled, said bolt having a head portion aligned with the key aperture and normally engaging said key, thereby retaining the bolt in position.

4. A bolt for holding the parts of cushioning mechanism assembled, comprising a shank portion, and an integral head at each end, one of said heads being elongated laterally to provide locking lugs for engagement with looking shoulders on associated mechanism, the outer surface of said elongated head being bifurcated to straddle an edge portion of an associated draft key.

5. Cushioning mechanism comprising a body portion and cushioning means at each end comprising a longitudinally acting spring, friction elements, a central wedge between said friction elements, and a bolt for connecting each wedge to said body portion, said bolts each having a head at eachend, one head of each bolt being elongated, and said central wedges and body portion having longitudinally extending slots for receiving said elongated heads, the wedge slots being laterally elongated and the corresponding body portion slots being laterally elongated in the direction of elongation of the wedge slots, so that each bolt may have its elongated head inserted through its wedge slot and on into the corresponding body portion slot and then locked in place by turning approximately 90 about its axis, said body portion having pockets extending from the slotted portions, in planes disposed approximately at right angles to the planes of elongation of the corresponding body portion slots, receiving an end portion of said elongated head, and preventing turning thereof when the head is pulled therein by the associated spring.

6. Cushioning mechanism comprising a body portion formed with a transverse aperture for receiving a connecting draft key and cushioning means at each end comprising a longitudinally acting spring, friction elements associated with said spring, a central wedge between said friction elements, and a bolt for connecting said wedge to said body portion, said bolt having an integral head at each end, one of said heads being elongated, and said central wedge and body members having normally registering elongated slots for receiving said elongated heads, the body portion having pockets extending from the slotted portions in planes angularly disposed to the planes of elongation of the corresponding body portion slots, whereby the bolts may be locked in place, after their elongated heads have been passed through the wedge and body slots, by turning about their axes until the heads fit in said body portion pockets, sai-d draft key, when in place, normally being disposed between the adjacent heads of said bolts and holding them in locked positions by preventing movement thereof toward each other.

.7. Cushioning mechanism comprising a body portion, a helical spring barrel disposed at each end of said portion, a seat for each end of each spring barrel, cooperating segmental friction shoes arranged in pairs, the members of each pair being anchored to said seats, a central wedge member acting between said friction shoes for pressing them together, said central member being in wedging engagement with the inner friction shoes, and bolts for holding the parts assembled With said body portion, each bolt having a head at each end, one of said heads being laterally elongated and said body member and the outer associated parts having elongated slots for receiving said elongated heads, the other head of each bolt being too big to pass through the slots, each bolt being locked in place, after its elongated head has passed through the corresponding elongated slots, by turning about its axis until an elongated portion of the head overlies the adjacent edge of the slotted portion.

8. Cushioning mechanism comprising a body portion slotted for receiving a draft key, a cushioning unit disposed at each end of said'body portion and each unit comprising a coil spring, shoe means flanged at one end and normally acting on the corresponding end of said spring, a plurality of friction elements engaging surfaces on said shoe means on the opposite side from said spring, and formed with inclined friction surfaces, and wedge means with correspondingly inclined friction surfaces engaging the inclined friction surfaces on said friction elements, said friction elements having abutment portions at their ends acting on the other end of the associated spring, members of said units extending inward beyond the outer surfaces of said body portion and bifurcated so as to straddle edge portions of the key when in place.

9. Cushioning mechanism comprising a longitudinally acting spring, friction elements, a central wedge extending from one end between said friction elements, a member disposed at the other end of said spring, and a bolt for connecting said central wedge to said end member, said bolt having a head at each end, one head being laterally elongated and said central wedge and end member having longitudinally extending slots for receiving said elongated head, the wedge slot being laterally elongated and the corresponding end member slot being laterally elongated in the direction of elongation of the wedge slot, so that the bolt may have its elongated head inserted through its wedge slot, and on into the end member slot, and then looked in place by turning approximately 90 about its axis, said end member having a, pocket extending from the slotted portion in a plane disposed approximately at right angles to the plane of elongation of said end member slot receiving the end portion of said elongated head, and preventing turning thereof when the head is pulled therein by said spring.

10. Cushioning mechanism comprising a body portion formed With a transverse aperture for receiving a connecting draft key, and cushioning means comprising a longitudinally acting spring, friction elements associated with said spring, a central wedge between said friction elements, and a bolt connecting said wedge to said body portion, said bolt having an integral head at each end, one of said heads being elongated, and said central wedge and body member having normally registering elongated slots permitting the passage of said elongated head, but preventing the passage of the other head, the body portion having a, pocket extending from the slotted portion in a plane angularly disposed to the plane of elongation of the body portion slot, whereby the bolt may be locked in place, after its elongated head has been passed through the wedge and body slots, by turning until the head fits in said pocket, said draft key, when in place, normally having an edge engaging said elongated head and holding it in locked position by preventing movement thereof out of said pocket.

11. Cushioning mechanism comprising a body portion, a helical spring barrel disposed at one end of said portion, a seat for each end of said spring barrel, shoes arranged in pairs, the members of each pair being anchored to said seats, a central wedge member acting between said friction shoes for pressing them together, said central member being in wedging engagement with the inner friction shoes, and a bolt for holding the parts assembled with said body portion, said bolt having a head at each end, one of said heads being laterally elongated, and said body member and the part at the opposite end of said spring having elongated slots for receiving said elongated head, the other head of said bolt being too big to pass through the slots, whereby said bolt is locked in place after its elongated head has passed through the elongated slots by turning about its axis until an elongated portion of the head overlies the adjacent edge of the slotted portion.

12. Cushioning mechanism comprising a body portion, slotted for receiving a draft key, a cushioning unit disposed at one end thereof and comprising a coil spring, shoe means flanged at one end and normally acting on the corresponding end of said spring, a plurality of friction elements engaging surfaces on said shoe means on the opposite sides from said spring and formed with inclined friction surfaces, and wedging means with correspondingly inclined friction surfaces engaging the inclined friction surfaces on said friction elements, said friction elements having abutment portions at their ends acting on the other end of the spring, a member of said unit extending inward beyond the outer surface of said body portion and bifurcated so as to straddle an edge portion of said key when in place.

13. Cushioning mechanism comprising a body portion formed with side walls and a transverse cooperating segmental frictionweb connecting said walls, cushioning means associated with said body portion and including a wedge and retaining bolt engaging said wedge, said web having a slot therethrough adapted for the reception of an end of said bolt during assembly of the parts, said side walls having slots disposed entirely on the opposite side of said web from said wedge, and a key passing through said slots in the side walls and adapted to limit movement of said gear, said key being positioned adjacent an end portion of said bolt to limit inward movement thereof during compression of the mechanism.

14. Cushioning mechanism comprising a body portion slotted for receiving a draft key, cushioning means associated with said body portion and including a bolt detachably securing said cushioning means to the body portion, said bolt having a head portion normally aligned with said key slot said draft key being adapted to engage said bolt head for preventing inward movement thereof.

15. Cushioning mechanism comprising a body portion slotted for receiving a draft key, cushioning means associated with said body portion, a bolt having a unitary head on one end thereof detachably securing said cushioning means to the body portion, said head normally aligned with said key slot and adapted to engage said draft key, thereby restricting the inward movement of said bolt.

16. Cushioning mechanism comprising a housing having a pocket at each end, said pockets being defined by longitudinal walls and a transverse wall, friction blocks movable laterally in said pockets, a wedge block extending into each pocket having a tapered portion interposed between said friction blocks, resilient means disposed between said friction blocks and longitudinal walls, said resilient means being positioned outwardly of said transverse wall and being substantially coextensive with each pocket, additional resilient means disposed between said wedge blocks and transverse wall, a bolt for limiting the movement of each wedge block away from said friction blocks, said bolt having an elongated head at one end thereof and said transverse wall and wedge blocks having elongated slots for receiving said elongated head, said bolt being locked in place after insertion by turning approximately 90 degrees about its axis.

EMIL H. BLATTNER.

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