US3101434A

US3101434A - Latching mechanism for electroresponsive relay

Info

Publication number: US3101434A
Application number: US780998A
Authority: US
Inventors: Kitscha Hector
Original assignee: Cutler Hammer Inc
Current assignee: Cutler Hammer Inc
Priority date: 1958-12-17
Filing date: 1958-12-17
Publication date: 1963-08-20
Anticipated expiration: 1980-08-20

Description

Aug. 20, 1963 .H. KITSCHA 3,101,434

LATCHING MECHANISM FOR ELECTRORESPONSIVE RELAY Filed D60- 17, 1958 2 Sheets-Sheeti H. KlTSCHA Aug. 20, 1963 LATCHING MECHANISM FOR ELECTRORESPONSIVE RELAY 2 Sheets-Sheet 2 Filed Dec. 17, 1958 I United states Paten .0

LATCHING MECHANISM FOR ELECTRO- RESPONSIVE RELAY Hector Kitscha, Milwaukee, Wis, assignor to Cutler- 1 Hammer, 1110., Milwaukee, Wis, a corporation-05f .Delaware Filed Dec. 17, 1958, SB?- No. 780998 9 Claims. (11317-187) I the contacts in one condition after momentary energization of the operating coil until released. Several types of latching mechanisms arepresently available for this purpose but, while generally satisfactory, they have been found wanting in some respects.

Accordingly, it is anobject of this invention to provide improved latching mechanisms.

Another object is to provide improved latching mechanisms which, after having performed a latching operation,

are releasable either manually, mechanically, or electroresponsively. i

, Still another object is to provide improved latching mechanisms of the aforesaid character which are particconnectable to supply line L1 through the normally open contacts 18a of a pushbutton switch 18 and. terminal conciprocably movable with respect to frame 13 and which is normally biased in an upward position, as shown in FIG. 1, by a helically shaped compression spring 2%) disposed between an integrally formed annular flange on armature member 19 and a cross memberof relay frame 13. An airgap exists between core 14 and relay armature 19 and the relay armature is adapted to be attracted toward core 14 when the latter is magnetized in response to energization of operating coil 15. Relay, armature 19 carries an electrically conductive bridging contact 21 which is suitably insulated therefrom and which is adapted to make connection between the

stationary contacts

22 and 23 supported by and'insulated from relay frame 13 .when the relay armature 19 is attracted downwardly. Stationary contact 22 is electrically connected to line L1 and stationary contact 23 is connected to one side of a suitable load device 12 whose other side is connected to line L2. As FIG. 3 shows, the top of frame 13 of relay device 11 isprovided with a hole 1311 which is adapted I to accommodate a shaft 29 of latching mechanism 10.

ularly well suited for use with electroresponsive relay devices.

A further object is to provide improved latching mechacharacter which are reliable in opnisms of the aforesaid er-ation, are readily adapted to a variety of applications, lend themselves well to mass production techniques, and are relatively economical to produce.

Otherobjects and advantages of the invention will hereinafter appear.

The accompanying drawing illustrates onegpreferred embodiment of the inventiomit beingunderstood that the embodiment shown is susceptible of various modifications with respectto details thereof without .departing from the scope of the appended claims.

In the'drawing:

FIGURE 1 is a view, partly in elevation and partly schematic, showing a preferred form of latching mechamsm incorporating the invention employed with a simplified formof relay device;

FIG. 2 is an enlarged top plan view of the latching mechanism shown'iri FIG. 1

FIG. 3 is a cross sectional viewof the latching mecha-'v nism taken along line 3-3 of FIGJZ; and

FIG. 4 is another cross sectionalview taken along line 4-4 of FIG. 3.

The construction of latching mechanism 10 is best understood by referring to FIGS. 1, 2, 3 and 4 together, whereinsimilar portions of the mechanisms have been designated by similar reference numerals.

Latching' mechanism 10 comprises a fiat, ri gid, metal base plate member 25 which is provided with four integrally formed, outwardly radiating, spaced apart

projections

25a and 25b, seen in FIG. 1, and 250 and 25d, seen in FIG. 3 Each projection may be understood to be provided with a mounting hole (not shown) with adapts the base plate 25 to be secured to the top of relay frame 13.1 As FIG. 3 shows, base plate 25"isprovided with a circular hole 26 through the center thereof which is adapted to accommodate a cylindrical, magnetiza-ble core piece 27 which is secured therein, preferably by welding. 'Co're piece 27, which is provided with a cylindrical bore 28 which accommodates a shaft 29 hereinafter more particularly described, is adapted at its upper end to accommodate'an annularly shaped shading coil 32, formed of copper or the like, which is press-fitted thereon and tightly secured in place by an annular'ly shaped steel sleeve 33 which is also press-fitted. Shading coil, 32 serves, in conjunction with a coil unit 34, hereinafter described, to afiord a resultant magnetic flux field whencoil unit 34 is energized, which reduces vibration and chatter in latching mechanism 10 if the coil unit 34 is energized from an A;-C. power supply. I

A cast coil unit 34, which overlies base plate 25 and encircles core piece 27, is adapted tobe energized to effect magnetization of the core piece, as will hereinafter appear. A shim 35 is disposed between coil unit 34 and base plate 25 to ensure a good fit. Coil unit 34 comprises a continuous, insulated conductor wire 36 (shown sche- Referring first to FIG. 1, the numeral 10 designates a 0' preferred form of latching mechanism incorporating'the invention which is shown associated with'a simplified form of electroresponsive relay device 11. As will hereinafter appear, the electroresponsive portions of latchingrnechanism 10 and relay device l1 and a load device 12 are adapted to be energized from a suitable source of A.-C. or D.-C. electrical power supply comprising the lines L1 and L2.

Relay device 11 comprises a rigid frame member '13 which is provided with a magnetizable core 14' around which an electroresponsive operating coil 15 is suitably arranged. Operating coil 15 is provided with two te'rminal connectors 16 and 17. Terminal connector 16 is matically in FIG. 3) wound or coiled and ,then ,cast or potted in an insulating compound 37, such as epoxy resin or the like, which serves to rigidify, strengthen and electricallyinsulate the coiled conductor. As FIGS. 1 and 2 make clear, a pair of

electrical terminal members

38 and 39, which may be assumed to be electrically connected to opposite ends of conductor wire 36 of coil unit '35, extend through and are mechanically supported by the insulating or potting material 37 on opposite sides of the coil unit. -It will be understood from FIGS. 1 and 2 that terminal member 38 is electrically connected to supply line L1 and that terminal member 39' is electrically connectable to supply line L2 through the normally open contacts 40a of a pushbutton switch 40.

Latching mechanism 10 further comp-rises a rigid frame member 41 which serves to trap coil unit 34' in place and which also affords support for a hollow housing member 42 hereinafter more particularly described. Frame memher 41 hasfour downwardly depending

legs

41a, 41b, 41c and 41d which terminate in flanges which rest on the

y projections

25a, 25b, 25c and 25d, respectively, of the 'base plate 25.{ It is to be understood that each flange is provided with a mounting hole (not shown) which regis- V ters with the mountinghole (not shown) in the respective projection. Thus, four identical screw bolts 43 secure the frame 41 to the base plate 25 and secure the latching mechanismto the top of the relay device 11. The flat main portion of the frame 41 of latching mechanism 10 I is provided with an aperture 44 which, as FIG. 3 shows,

tends axially therethrough. The portion of bore 45 adjacent the upper end of housing 42. is preferably cylin- 1 drical and is provided with an annular flange 45a therewithin. The portion of bore 45 below the cylindrical portion is conical in shape and flares downwardly.

A ball cage member 46, which is formed of suitable magnetic material such' as iron or steel,1is disposed within the bore 45 of housing member 42 and is slidab-ly movable with respect thereto.

Ball cage 46 is substantially cylindrical in form andis provided with: a cylindrical bore 47 extending axially therethrough which is adapted v to accommodate the shaft 29 hereinafter described. The

upper end of ball cage 46 is of smaller diameter thanthe remainder thereof and is adapted to fit within the narrowest portion of bore 45 of housing member 42. v The upper endof ball cage 46 is further adapted to accommodate a washer-like member 48 which is rigidly secured thereto.

Washer-like member 48, which is preferably formed'from aluminum for greater lightness, is of greater diameter than thehousing member. 42am a helically-shap-ed com pression spring 49 is disposed between the bottom surface of the washer-like member and the upper surface of the shoulder 42a of housing member 42. Spring 49 tends to, bias the ball cage 46 toward the top of housing mem- V ber 42 but annular flange 45a within bore 45 of. housing member 42 cooperates with a shoulder 46d ofball cage i accident-ally moved downward slightly in response to vibration it would look in a position other than normal.

tion 31 are preferably beveled or sloped as f FIG. 3.

shown in FIG. 3 shows the latching mechanism'ltl in its normal or unlatched condition. In this condition, ball cage 46 is biased outwardly of housing member 42 by spring 49 as far as flange a in bore 45 of the housing member permits. Furthermore, shaft29 is disposed so that grooved portion 3]. lies adjacent the balls c, Sdb

and 50c. In this position the halls are not in contact with the shaft 29, but substantial upward movement of the shaft is prevented since end'su-rface 31b of grooved portion 31 would be forced against the portion of the balls projecting into bore 47 of cage do and the balls would jam against the conical surface of bore 45 of housing member '42. Shaft 29 can be moved downwardly, however,

as will hereinafter appear. Itis preferred to provide shaft 29 with a grooved portion 31 which does not engage v the balls' when the shaft is in normal position in order to avoid downward creeping of the shaft if the device 10 were subjected tovibration. As will be apparent,- if

grooved portion 31 were omitted, upward movement of the shaft'Zf would still be prevented but if the shaft were The invention'operates in the following manner.

Referring first to FIG. I, assume that supply lines L1 v and L2 are energized, that the contacts 18a and Mia of the pushbutton switches 18 and 41), respectively, are open asshown, and that theconstituent elements of relay device 11 are in the positions shown. Further, assume that the components of latching device 10 are in the relative positio'ris shown in FIG. 3.

Suppose it is desired to energize load device 12 in response to momentary energization of the operating coil 15 of relay device 11 and to maintain the load energized even after the operating coil is deenergized. Closure of the contacts 18a of pushbutton switch 18 effects energizationpof relay coil 15, by establishing a circuit from supply line L1, through terminal 16, coil 15, terminal 17 and through contacts 18d to supply line L2. Energization of relay coil 15 eifectsmagnetization of relay core 14 which exerts an attracting force upon relay armature 19 thereby moving the latter downwardly against the bias of relay compression spring 2%. Bridging contact 21 on relay 46 to limit upward travel of the latter. Downward travel of ball cage 46 is limited by the size of the air gap between the cage and core piece 27. 'As FIGS. 3 and 4 show, ball cage 46 is provided with three apertures 46a, 46b and 46c which are spaced about the periphery thereeach aperture near the exterior surfaceof ballcage do is cylindrical in shape and the portion near the bore 47 of- I .the cage is conical in shape constricting inwardly from the cylindrical portion.

7 Each aperture communicates with the bore 47 ofball cage 46 and each is adapted to accommodate a steel sphere or ball bearing such as 50a, 50b, 50c. than the thickness of thewall of the ball cage 46.

'of at angular distances of 120 degrees. The portion of armature 19 is carried downwardly therewith and com pletes an electrical connection between

stationary contacts

22 and 23 on the frame 13 of relay 11. An ener f giZi-ng circuit forload' device 12 is thus established from V supply line L1, throughload device 12, stationary contact 22, bridging contact 21 andstationary contact 23. to .supply line L2. Load device. 12 remains energized as long as the stationary contacts are bridged.

Referring now to FIGS. 1 and 3 together, it will be understood that downward movement ofrelayarmature.

19 effects corresponding movement of shaft 29 oflatching mechanism 10 which is mechanically connected thereto.

As shaft 29 moves downwardly, the upper beveled surface the balls 50a, Sill) and 500 which is tran-smittedthrough The diameterof each ballbearing is greater The shaft 29, hereinbefore referred to, is preferably formed of non-magnetic material such as stainless steel.-

The shaft 29, which is substantially cylindrical in form, has alower end portion 36} which is adapted, as by threading, to be mechanically connected to the armature 19 of relay 11 hereinbefore described, and is movable therewith, as will hereinafter be described. I-f preferred, the

upper end of shaft 29 may be slotted, as at 29a, to accommodate a tool for facilitating adjustment of'the shaft with respect to the armature to which it attaches; The shaft 29 is also provided with a grooved portion 31 having a diameter which is less than'the main portion of the shaft. The end surfaces 31a and 31b of the grooved por- 31a of grooved portion 31 exerts a downward force on the balls to ball cage 46 forcing the latter downwardly "against the upward-bias of spring 49 of the latching mechanism 1%; Ball cage 46 moves downwardly sufficiently far so that the balls wen-50b and 500 can be i moved outwardly and the thicker portion of shaft 29 above grooved. portion 31 can move freely between the balls. Shaft 29 isrnoved downwardly by relay armature member 19 and should previously have been adjusted so that whenits downward travel stops, the top edge of the notched portion 31 of shaft 29 will lie below the center line of the balls. When shaft 29 stops moving downwardly, the tendency of compression spring 49 to'force the ball cage 4s upward causes the balls 56a, Stlband Stlc to f be wedged between the surface of the shaft 29 above grooved portion 31 and the conical wall of bore 45 of housing member 42 thus locking the shaft against upward movement,

When the

contacts 18a contacts

22 and 23 are still bridgedits outward travel stops. asthe shoulder 46d of of pushbutton switch 18 are opened to interrupt the energizing circuit for relay coil tends to bias the armature l9 upward. Upward movement of; armature 19 is prevented, however, because shaft 29 of latching mechanism 16 is locked against upward movement as hcreinbefore described.

by bridging contact 21 and the energizing circuit for load even though relay coil is deenergized. j The shaft 29 of latching mechanism 10 is releasable for upward movement by moving ball cage 46 downward- 1y to release the wedgingpressure exerted by the balls SOafStlb and 50b. Downward movement'of ballcage 46 with respect to housing 42 can be effected either manually or electromagnetically. p i, To effect manual release, ball cage 46 is moved downwardly by applying a force upon' disc like member 48. As the ball cage 46 descends, the bells 50a, Sill) and 50c no longer are forced between the surface of shaft 29 and the wall of the conical portion of the-bore 45 of the hou sing 42. Shaft 29is free to move upwardly. and does sointerrupts the energizing circuit for theload 12.

Thus, the stationary device '12 is maintained core 14 becomes demagnetized and relay spring j Toefliect electromagnetic release-of latching mechanism 7 10, pushbutton switch 40 is depressed to establish an energizing circuit for coil 45 fromsupply line L2, through I thecontacts 40a of switch 40, coil terminal '38," coil 34 and coil'terminal 39 to supply line Ll. Upon energizaiii-on of coil 34 a magnetic flux field is established which effects magnetization of core piece 27; .Thus magnetized,

core piece, 27 exerts an attracting force upon ball oage td which moves downwardly with the results hereinbefore described to effect release of shaft 29. Upon release of pushbuttonswitch 40 the contacts thereof open to interrupt the energizing circuit for-coil 34; Coil 34 deenergizes, the magnetic field decaysv and core piece'27 no longer exerts'an' attracting force upon ball cage 46. Compression spring 49 is thus free to move the latter member f 'upw ard as hereinbefore described.

It will be apparent tothose skilled in the art that latching mechanism 10 could be employed to latch relay contacts open instead of closed, as shown, or to latch some form of device, other than a relay, which operates the shaft 29 in the manner hereinbeforedescribed. r ,I claim: v

1. A latching device comprising:

(a) a movable member having a normal position and another position displaced from said normal position into which s'aid'membermay be locked;

, (b) band latching means for automatically locking said it movable member when moved to said other position to prevent return thereof to, said normal position until'it is released comprising? (c)' a member provided with an and at least one side of said aperture having a surface at an angle to the direction of movement of said movable member so thatthe opposite sides of said aperture converge in one direction and diverge in the opposite direction;

(11) aball carriage partly within said aperture and having a hole the-rethrough for accommodating said movable member for free movement relative to said ball carriage and being provided with at least one ball confining opening between said movable member and saidangular surface and a ball rotatably aperture therethrough modating a portion of said ball when said movable member is in said normal position thereby to preventswedging of said ball bet-ween said angular surface and said movable member and prevent locking of said movable member until the latter has been moved a predetermined distance intosaid other position;

(g) means for moving said movable member to said other position whereby a side of said recess bears against said ball to move said ball and said ball carriage against the force of said resilient means until said ball is provided with enough space to be forced out of said recess and is wedged between said angular surface and a portion of said movable member adjacent said recess thereby to lock said movable member in said other position and to prevent return thereof to said normal position;

(h) and electroresponsive means for moving said ball oarriage'against the force of said resilient means to release saidmovable member for return back to its normal position. I

2. The invention defined in claim 1, wherein said movable member is a round "shaft and said recess is an annular Y groove on said shaft, and said groove. having a predetermined length to prevent locking of said shaft until it 3. The invention defined in claim 1, wherein:

(a) said ball carriage has an end extending beyond I said apertured member;

(b) a flange on said ball carriage having a diameter longer than the diameter thereof at said ball conlining opening; I

, (c) a and said resilient means comprises a helical compressi-on spring surrounding said ball carriage and being compressed between said flange and a stationary portion'of said device to bias said ball carriage in the latching direction. I

4. The invention defined in claim 3, wherein:

(a) one end of said ball carriage is uncovered to allow manual movement of said ball carriage against the force of said spring to release said movable member. l

5. The invention defined in claim '1, wherein said electroresponsive means comprises:

I (a) an electrically energizable coil having a center hole I and having an end portion extending partway into the center hole of said coil from the other side thereof toform an air gap with said core means whereby energization of said coil causes said core'means to attract said ball carriage through said air gap and against the force of said resilient means to release said movable member. 6'. A latching device comprising: (a) an axially movable shaft having a normaltposiltion and another position axially displaced from said normal position into which said shaft may be locked; (b) and combined latching means and electroresponsive releasing means automatically operating in response to movement of said shaft to said other position when said electroresponsive releasing means is deenergized for locking said shaft in said other position to prevent return thereof to said normal position and operating in response to energization of said electroresponsive releasing means for unlocking said (b)v magnet-izable core means extending partway into 7 '55 1 (c) said ball carriage being of magnetlzable material shaft to allow return thereof to saidinormal position, said combined latching means and electroresponsive releasing means comprising: I

(c) an energizing c'oil having a center hole;

(d) a magnetizable path for the flux developed by said coil when electrically energized and having an armature air gap, said path comprising:

'(e) a magnetizable member having an aperture therethrough in alinement with the center hole of said coil, a portion of the internal surface of said member {(g) a combined ball carriage and armature, extending I through said aperture and having ahole therethrough slid-ably accommodating said shaft and being provided with a plurality of angularly spaced ball confining openings between said shaft and said 'frustoconical surface and-'ballsrotatably movable in'said openings each having a diameter greater than the v thickness of the ball carriage wall adjacent said openings; v

(h) resilientmeans biasing said combined ball carriage and armature in the direction from the larger end toward the sm-allerend of said frusto-conical surface and being effective upon movement of said shaft to said other position to wedge said balls between said V frusto-conical surface and said shaft to lock the latter from movement back to said normal position;

i (i and one end of said combined ball carriage and armature extending intospaced relation with an end OfSflld core piece to'form'amagnetizable air gap therebetween' whereby energization of said coil causes magnetic movement-of said 'combined'ball carriage and armature through" said air gap against the force of said resilient means to release said shaft.

7. The'invention defined in claim 6, together with:

(a) an annular groove in said shaft and at a point along said shaft which is between said balls when said shaft is in one of said positions.

' 8. In a latching device, in combination:

(a) amovable shaft having a normal position and an axially displaced position;

(b) latching means for locking said'shaft when moved to said axially-displaced position to prevent return thereof to said normalposition comprising:

v(c) a member having a round tapered bore diverging in one direction;

(d) a movable ball carriage within said 'bore having a smaller bore therethrough sli'dably accommodating I said shaft and having means confining and rotatably supporting a plurality of balls angularly spaced from one anotheraround said shaft for frictional 'engagemen t -betweensaid shaft and said tapered bore;

shaft between said balls when said shaft is in its'normal position and havinga length along said shaft to prevent locking of said shaft until said shafthas been moved a predetermined distance to said axially displaced position;

(1) means biasing said ball carriage in. the direction of the smaller end of said tapered borewhereby axial movement of said shaft a predetermined distance in the other direction causes said balls to rise out of said groove in said shaft against the force of said biasing means and to be wedged between the larger portion of said shaft and the surface of said tapered (l) and (g) a recess in sai d shaft (e) a groove around said shaft at a point along said hereunder the force of said biasing means to prevent returnof said shaft to its normal position;

. g) and electromagnetic unlatchingmeans comprising '(h) an operating coil surrounding said shaft an end portion of said ball carriage;

(i) and a magnetizable path for the, flux produced said coil when energized comprising:

(j) a magnetizable core'piece extending partway into I said coil and having a bore therethrough for slidably accommodating said shaft; :-('k) said member and said I of magnetizable material and one end of said'ball,

carriage being spaced a'predetermined distance from an end of said core piece to form an air gap in saidaround the outside of said coil; a

,'(m) and energization of said coil causing said ball I carriage to operate as an armature and'move in I said air gap toward said core piece whereby tore I lease said balls fromengagement'with said shaft and allow return of the latter to its normaljpositio'n.

V 9. -In a latching device, in combination:

(a) an axially movable shaft having a normal position and another position axially-displaced from said normal position intowhich said shaft may be locked;

b) latching means for automaticallylocking said shaft when moved to said other position to preventlreturn thereof to said normal position untilit is released tion comprising:

(0) a member having a tapered aperture tlieretlirougl V diverging inone direction; I 1 (d) a movable ball carriage extending through and beyond the ends of saidtapered aperture having a hole therethrough slidably accommodating said shaft 7 and-being provided with at least one ball-confining; opening between said shaft and the surface of sai'd tapered aperture and a ball rotatably accommodated a diameter longer than the I in said opening having I I thickness of the wallof said ball carriage adjacent said opening; I 7 (e) resilient means biasing said ball carriage in the di- I .rection, of the converging ,end of said tapered aper- I 4m i I I I .I (f) cooperating means on said member and said ball I carriage limiting relative, movement therebetween under the force of said biasing means;

to prevent rwedging of s'aidjball between said shaft andsaid surface of said tapered aperture;

t (11) means for moving said shaft'to, said other position .whereby said ball carriage is movedagainst the force;

if of said biasing means and said ball is forced out of I said recess and is wedged between said surface of,

saidtapered aperture and said shaft when the latter is released. by said moving means thereby to lock said shaft in" said other position;

(i) and-one end of said ,ball carriage extending beyond an end of said tapered aperture and being exposed for manual movement to release said shaft for return to its normal position,

References Cited in the file of this patent UNITEDSTATES PATENTS 999,850 7 Palmer 1 Aug. 8, 1911 1,582,987 Hart May 4, 1926 2,535,095 Schwartz et al. ..I in; Dec. 26, 1950 2,632,425 Grover Mar. 24, .1953 r 2,710,320

ball carriage being made magnetizable vmeans completing said path I and for preventing locking of said shaft untilit is I moved a minimum distance from said normal posi-v I receiving a portion of said I ball when said shaft'is intits normal position thereby;

Weinfunt June 7, 1955

Claims

1. A LATCHING DEVICE COMPRISING: (A) A MOVABLE MEMBER HAVING A NORMAL POSITION AND ANOTHER POSITION DISPLACED FROM SAID NORMAL POSITION INTO WHICH SAID MEMBER MAY BE LOCKED; (B) AND LATCHING MEANS FOR AUTOMATICALLY LOCKING SAID MOVABLE MEMBER WHEN MOVED TO SAID OTHER POSITION TO PREVENT RETURN THEREOF OF SAID NORMAL POSITION UNTIL IT IS RELEASED COMPRISING: (C) A MEMBER PROVIDED WITH AN APERTURE THERETHROUGH AND AT LEAST ONE SIDE OF SAID APERTURE HAVING A SURFACE AT AN ANGLE TO THE DIRECTION OF MOVEMENT OF SAID MOVABLE MEMBER SO THAT THE OPPOSITE SIDES OF SAID APERTURE CONVERGE IN ONE DIRECTION AND DIVERGE IN THE OPPOSITE DIRECTION; (D) A BALL CARRIAGE PARTLY WITHIN SAID APERTURE AND HAVING A HOLE THERETHROUGH FOR ACCOMMODATING AND MOVABLE MEMBER FOR FREE MOVEMENT RELATIVE TO SAID BALL CARRIAGE AND BEING PROVIDED WITH AT LEAST ONE BALL CONFINING OPENING BETWEEN SAID MOVABLE MEMBER AND SAID ANGULAR SURFACE AND A BALL ROTATABLY ACCOMMODATED IN SAID OPENING HAVING A DIAMETER GREATER THAN THE THICKNESS OF THE WALL ADJACENT SAID OPENING; (E) RESILIENT MEANS BIASING SAID BALL CARRIAGE IN SAID ONE DIRECTION;