US2047468A

US2047468A - Revolving door speed control

Info

Publication number: US2047468A
Application number: US757952A
Authority: US
Inventors: Thurloe M Hagenbook
Original assignee: INTERNAT DOOR Co
Current assignee: INTERNAT DOOR Co; INTERNATIONAL DOOR Co
Priority date: 1934-12-17
Filing date: 1934-12-17
Publication date: 1936-07-14
Anticipated expiration: 1953-07-14

Description

July 14 1933 T. M. HAGENBOOK 2,047,468

REVOLVING DOOR SPEED CONTROL Filed Deo. 17, 1954 5 sheets-sheet 1 E EET-l IN V EN TOR.

July 14, 1936. T. M. HAGENBOOK 2,047,468

' REVOLVING DOOR SPEED CONTROL Filed Dec. 17, '1934 5 sheets-sheet 2 lll/IA INVENTOR.

BY WA AToRNEY 7 July 14, 1936.

'T. M. HAGENBCOK REVOLVING DOOR SPEED CONTROL 5 Sheets-Sheet 3 Filed Dec.

jr- I v Y 1v- July 14, 1936. T. M. HAGENBOOK 2,047,468

REVOLVING DOOR SPEED CONTROL Filed Dec. 17, 1934 5 Sheets-Sheet 4 l w f@ f Q f .E 0 y A A..

Q0 INVENTOR. Ln WIM/d50@ Qecjemmv, :u: Byf df Q I y f-:TToRl-VEY July 1'4, 1936- T. M. HAGENBooK REVOLVING DOQR SPEED CONTROL Filed DeC. 17, 1934 5 Sheets-Sheet 5 UTET. l

' INVENTOR. Z gfZ/wveoe 9m. gogwoo/l) f BY WA ToRNEY /f IWI HIM

Patented July 14, 1936 UNITED STATES PATENT OFFICE Thurloe M. Hagenbook,

Evansville, Ind., assignor,

by mesne assignments, to International Door Company, Evansville, Ind., a corporation of Illinois Application December 17, 1934, Serial No. 757,952

17 Claims.

My invention relates broadly to speed control mechanism and more particularly to a construction of speed control mechanism for revolving doors.

My invention is directed to that class of speed control mechanism for revolving doors of the type shown in my Patent 1,946,160, granted February 6, 1934, based on application filed September 10, 1932; and my copending application 689,633, flled September 15, 1933, for Revolving door speed control now Patent 2,029,318, granted February 4, 1936.

One of the objects of my invention is to provide a highly compact construction of speed control for revolving doors, whereby the speed control may be installed and operated in conned places.

Another object of my invention is to provide a construction of speed control for revolving doors, in which the speed at which the mechanism becomes operative for the control of the revolving doors may be readily adjusted from a position adjacent the revolving door.

Still another object of my invention is to provide a construction of speed control mechanism for revolving doors which is also effective to brake the rotation of the door under conditions of sharp deceleration.

A further object of my invention is to provide a construction of revolving door speed control in which a centrifugally operated mechanism is effective to retard excessive acceleration, and in which an auxiliary mechanism is provided for effectively braking the door under conditions of rapid deceleration.

A still further object of my invention is to provide a simplied construction of centrifugally operated mechanism for revolving doors, and a coacting cam actuated mechanism for controlling the speed of the revolving door, and braking the revolving door under conditions of rapid deceleration.

Other and further objects of my invention reside in the construction and arrangement of parts of the revolving door speed control set forth more fully in the speciiication hereinafter following by reference to the accompanying drawings, in which:

Figure 1 is a top plan view of my improved speed control used in connection with the control of revolving doors; Fig. 2 is a central vertical longitudinal section through the speed control mechanism, taken substantially on line 2-2 of Fig. 1 and showing the elements in normal position; Fig. 3 is a transverse vertical section taken substantially on line 3-3 of Fig. 1, but Showing the (Cl. 18S-180) centrifugal mechanism in position for braking the revolving door under conditions of excess speed; Fig. 4 is a similar view showing the position of the tumblers, friction Wheel, and friction disc under conditions of excessive deceleration which will result in the stoppage of the revolving of the door; Fig. 5 is a horizontal section taken on line 5 5 of Fig. 4 looking in the direction of the arrows; Fig. 6 is a horizontal section through the revolving door speed control mechanism taken on line 6 6 of Fig. 2; Fig. 7 is a detailed horizontal section through the tumbler supporting housing taken substantially on line 1-1 of Fig. 8; Fig. 8 is a central vertical longitudinal section taken on line 8-8 of Fig. 7; Fig. 9 is a detailed top plan view of the housing containing the mechanism for the improved speed control; Fig. 10 is a central vertical longitudinal section taken on line lll- I0 of Fig. 9; Fig. 11 is a transverse vertical section on an enlarged scale taken on line l ll I of Fig. 9; Fig. 12 is a top plan view of the cover plate used in association with the housing; Fig. 13 is a central vertical longitudinal section of the same, taken on line l3-|3 of Fig. 12; Fig. 14 is a detailed central vertical longitudinal section of one of the brake elements used in connection with my improved speed control; Fig. l5 is a top plan view thereof; Fig. 16 is a detailed side elevation of one of the centrifugally operated tumblers; Fig. 17 is a front elevation thereof; Fig. 18 is a horizontal section taken on line l8-I8 of Fig. 16; Fig. 19 is a horizontal sectional view taken on line I9-I9 of Fig. 2; and Fig. 20 is a detail view of a portion of Fig. 19 showing parts in an operating position.

Referring to the drawings in detail, the speed control mechanism is shown mounted within the casing located adjacent the top of the revolving door structure. The casing is formed by a mulplicity of coacting parts which I have Vrepresented by characters l, 2, 3, and 4. The several parts of the housing are shaped to provide bearing supports, and Aarranged to conform with the contour of the elements constituting the parts of the speed control mechanism. It will be noted that part I is recessed at la and is apertured at Alb to allow the passage of shaft 5, and to provide a housing for the roller bearing structure 2U. 'I'he part 4 of the casing is recessed at 4a and is apertured at 4b to allow the passage of the lower end of shaft 5 and to form a housing and support for the roller bearing structure 2|. 'I'he shaft 5 has a diametrically extending aperture 5c there-l in, through which the laterally extending member 24 projects. The laterally extending member 24` is connected with block I9 centered concentrically with respect to the internal tubular portion of shaft 5. The block I9 is balanced between two

coil springs

28, and 28 as will be more fully described hereinafter. The upper coil spring 28 fits within the socket portion 5b of shaft 5. The lower coil spring 2B fits between the block I9 and the adjustable plug 29, which is screwthreaded into the lower end of the tubular shaft 5. The adjustable plug 29 has a tool receiving. socket 29a, into which a suitable wrench maysb'e inserted for varying the effective tension, on :the lower coil spring 28 as the screw-threaded plug 29 is advanced or retractedV with respecttothe internally screw-threaded shaft, 5. The casingr of the speed control mechanism is so mounted with respect to the revolving door structure, that the adjustable plug 29 may be readily engagedby a tool inserted through the aperture 35 in-theceiling structure 36, adjacent the revolving door assemblyrepresented generally at 31 and'38ll The entirecasing structure of thel revolving door speed control-"issuch that the casingwill readily tlbetween the beams 38,' on'. which the channel irons or :rails 39-are erected. Aportion of the casing 3 depends-downwardly betweenthe rails 39; thereby allowing installation of the: speed control` equipmentLin a'confined space.-

The Y revolving door-assembly comprisingrevolving-Jdoor vwings 3`I`is carriedby shaftrdll; the upper-endofwhich is supported by the wheeled carrienlihaving rollers Mfwhich are guided :by the-rails 39;- The spindle 43"-which'istdrven-by therevolving door positivelydrives shaft I8 which is-'keyed by suitable key andkeyway to the gear I I; Thegearl I risvformedby an annularportion having a dependingskirt withtheedge thereof milled to provide gear teeth represented at IIa which mesh with ythe'gear I2"which is journaled orrstudlI 5' serving as an axis .for v'the ball bearing mounting 23`for thezgear I2.v The-gear- I2 is; in turn,` meshed with the teethI of gear I 3 mounted onshaft I3a: Shaft I3a-is journaledin suitable bea-rings. represented at 22. The' bearings 22 l are mountedf'inrecesses.providedin parts of the'casing Land-'2.Y The casingshownf at I-has-a lower recess. therein shown at Ic. 'I'hefcasingfsection 2 hasan upwardlyprojecting recess-therein shown :3.t12'ct',v which recesses serveas enclosures for-the bearings 122 which support the` shaft I 3a'. The shaft I3-carries thegear` llt-which meshes -with they geariteeth'5cvwhich are `cut inthe upper end of -theshaft-fS. The shaft 5 provides `amounting for Vthey friction disc IOL which is-secured-toshaft 5 by means of a key and keyway represented" at loa-which allows friction'disc ID- tofbe positively driven byshaftS-and yet, which permits the displacementof-friction disc I 0in position along-the axisaof theI shaft. The friction discf Ill'has a hub: portion: formed-integrally therewith terminating in the-lower edgeportion which-is provided with a multiplicity of serrations forming a plurality of step-by-step `cam` surfaces'V indicated at IOc; Theicam surfaces Ic coact with correspondinglyj shaped successive cam surfaces 8c formed'on the hub portion 8b of the circular carrier 8; 'Ilriecircular carrier 8.is providedwith alignedapertures 8a in the` rotatable sleeve portionthereof through which the. laterally extending member 24. passes. The apertures 8aV are verticallyfextending. slots, larger in cross-section than :thef bar, 24. which .permits thebar to. move vertically;in-thefaligned slots:H The; circular. carr- 755 rier.- 8 isgprovidedA withi a .plurality of.: oppositely disposed pockets 8d which provide housings for centrifugal weights 9. The construction of centrifugal weights 9 is shown more clearly in Figs. 16, 1'7 and 18. It will be seen that the weights are not positively connected with the circular carrier 8, but are so shaped by means of the projecting p ortion 9a thereon that under conditions of centrifugal force produced by rotation of circular carrier 8', the center of gravity of weights 9 which is-above the point of contact of the projecting portions 9a tends to travel outwardly. 'Ihe displacementofxthe'center of gravity of the weights 9 results in a rocking movement of weights 9 from theI position illustrated in Figs. 2 and 4 to the positionjillustratedin Fig. 3. The outward rocking of the weights 9 results in an upward displacement of the weights in the position illustrated in Fig. 3 placing-an upward thrust on the lower face of the frictionwheel 6. The friction wheel 6 has a frusto-conical friction surface 6a which tends to frictionally engage; a correspondingly shaped frusta-conical surface 3a1 formed on the interior wallof section 3:.of .the housing; A predetermined speed of rotation must be reached in order to. bring about that'degreeof centrifugal force necessary -1 to rockff the. weights- 9`for exerting the. upward shifton-fr'iction `disc 6:

The friction disc Eris counterbalancedby means of coilsprings- 28;` and 28 coacting with block I9.-4 Block I9-"carreslaterally extendingmember 24, which; in turn, carries -friction wheel B. The laterally extending member 24 is smaller in crosssection than the aligned apertures 5a which `extendcircumferentially. partly around shaft 5,

as shown. more clearly in Fig. 19,` so that the carrierl isrfree to shifter rotate with respect to shaft.52within limits `which are` sufficient to allow shiftingof the cam shaped faces 8c with respect tothe-cam shaped faces |00 of'friction disc I9. The lupper` coilspring 28:' tends to resistthe upward-"movement of'fr'iction wheel GS while the lower coil spring 28 tendsto: assistthe upward movement of friction wheel 6i The path of movementoffriction wheel `6"is guided by key and keyway-"connection 6b'. By provision ofthe adjustment plug- 29; the degree of centrifugal force, necessary to bring about the upward thrust of friction wheel Band overcome'the unbalanced condition ofcoilsprings 28 andv 28', may be determinedv withva high degree of'precision. To vary the con-trolof speed,l it is only necessary to vary the-tension on the lower coil -spring 28 by adjustment'of plug=29 When the door is sharply decelerated, the friction' wheelA Gfandthecarrier` 8 and centrifugal weightsi andIk associated parts become Yan independent driver'and operate to vexpend their kinetic energy.l In' other words, the mass of the carrier Wand' centrifugal weights-9 is such -that the carrier- 81- a-ndcentrifugalweights-9 tend to continue their rotative movement while friction disc ldecelerates with thedeceleration of shaft 5. Thistindependent drivingl power tends to move thel serrations constitutingfthe'plurality of cam faces-8 faster than thev rotation Ofserrations or cam-facessIDc on friction disc I0, as-'a result of which, friction disc I0 is raised or forced-lupwardly,4 guided by keyl and keyway- IUa, thereby driving friction disc I0' into frictional engagementfwith'the friction surface 3| on part I of the casing. The'frictional contact thus established tendsH to bring shaftY 5 to a stop thereby bringing. the revolving doors to a standstill. it`Wi-ll'b'e seen'that'rapid deceleration tends to` brake'A the revolving'door.

The several stages of operation of the revolving door speed control will be understood more clearly by considering the normal position of the parts illustrated in Fig. 2, and the successive positions of the parts illustrated in Figs. 3 and 4. In Fig. 2, the rotatable carrier 8 and the centrifugal weights 9 are shown in normal position, such as is experienced when rotating the revolving doors at normal speed. In this position, the frusto-conical face 6a of friction wheel 6 is disengaged from the frusto-conical face 3a of casing 3, and friction disc I0 is driven in disengaged relation with respect to friction surface 3|. This condition continues so long as the rotative speed of the revolving doors does not exceed a predetermined value, or is not abnormally decelerated. The normal relative position of the shaft 5 and carrier 8 is shown in Fig. 19, wherein shaft 5 drives carrier 8 through the connection by bar 24.

When the centrifugal action of weights 9 is brought into effect by an excessive speed of rotation, the friction wheel 6 is lifted, as illustrated in Fig. 3 for frictionally engaging the lfrustoconical face 6a thereof with the coacting frustoconical face 3a of casing 3. The relative position of shaft 5 and carrier 8 as shown in Fig. 19 is not changed in this operation, bar 24 having been displaced vertically in slots 5a and Sa upon the raising of friction wheel 6; and thus friction disc I0 is not displaced in position under these circumstances and continues to idly revolve in disengagement with respect to friction surface 3 I Braking of the revolving door is, therefore, effected for accelerated speeds.

Upon condition of sharp deceleration, however, the centrifugal weights 9 resume their normal position in pockets 8d of carrier 8, and the friction wheel 6 drops downwardly disengaging with respect to friction surface 3a of casing section 3. The mass of the friction wheel 6, the carrier 8, and the weights 9 is such, however, that their speed of rotation does not decelerate at the same rate as the speed of the friction disc I i! and hence, these parts operate as a driver, a's heretofore explained. Referring to Fig.l 19, when hub 8b becomes the driving shaft, bar 24 is controlled thereby and carried ahead of shaft 5 in the slots 5a, as shown in Fig. 20. The cam faces 8c formed on the hub 8b force cam faces Ic upwardly, thereby engaging friction disc IB with friction surface 3| resulting in the braking of shaft 5 to which friction disc I0 is keyed through key and keyway Illa as represented in Fig. 4.

'Ine driving ratio between the revolving door and the shaft 5 is approximately 1:25. That is to say, for each turn of shaft I8, there are twenty-five turns imparted to shaft 5. When the shaft 5 is rotated at too high a speed, the centrifugal mechanism becomes effective to brake shaft 5. However, if the deceleration of the revolving door becomes too great, the auxiliary braking mechanism constituted by friction disc I0 and friction surface 3| becomes effective to brake Shaft 5.

It will be understood that the braking mechanism is constituted by two independent systems which are not operative simultaneously, but successively. That is, at the time friction wheel 6 has the friction surface 6a thereof in engagement with friction surface 3a, the friction wheel I0 is free of engagement with friction surface 3|. Conversely, at the time that friction wheel 5 has its friction surface 6a out of engagement with friction surface 3a, the friction wheel I0 maybe engaged with friction surface 3|, if conditions of excessive deceleration should exist.

It will be understood that there is sufficient lost motion permitted in the movement of friction Wheel 6 to permit the displacement of friction wheel 6 according to the displacement and position of the weights 9. The friction wheel 6 is secured in position by means of bolts 35 which extend through the friction wheel and into plate 'I. Plate serves to confine laterally extending member 24 in position, which member has its opposite ends fitting somewhat loosely in sockets 6c disposed in friction Wheel 6. The oppositely disposed slots 5a in

shaft

5 and 8a in carrier 8 are of such size that friction wheel 6 is free to be displaced vertically under control of the centrifugal weights 9. Likewise carrier 8 and block I9 are mounted with respect to shaft 5 so as to rotate freely with respect thereto by the force of momentum under conditions of excessive deceleration of shaft 5.

The housing for the several parts of the speed control has been heretofore described in general terms and reference is made to Figs. 9-15 for a more detailed disclosure of the several parts constituting the housing. It will be seen that section of the casing is so shaped as to provide a compact housing for the inverted gear I I by the coaction of the upwardly projecting annular portion ld with the peripheral portion Ie. Section I of the casing is supported, as shown more clearly in Figs. 9 and 11 by means of flanges If having web members Ig interconnecting the flanges If with the casing I. The support for the shaft I 5 is indicated at lh adjacent the housing Ic which receives the ball race 22. The closure for the casing indicated at 2 is secured in position with respect to the flanged edge of section I of the casing by means of a coacting flange 2b and a plurality of bolt members 26.

I provide a special journal for mounting shaft I8 which I have indicated by means of sleeves I6 and |'I concentrically disposed interiorly of the upwardly extending annular portion ofsection indicated at Id.

The friction Wheel 6 is shown more particularly in Figs. 14 and l5 from which the interior construction of the friction wheel will be clear. The recesses disposed internally in the friction wheel 6 serve as seats for the plate 1 and the laterally extending member 24 secured in position by means of the bolts 36 extending through apertures 6d provided in the friction wheel.

The revolving door speed control of my invention comprises a relatively small number of parts and is relatively simple and inexpensive in production. I have found the arrangement of the parts of the mechanism highly practical and, while I have described my invention in one of its preferred embodiments, I desire that it be understood that modifications may be made and that no limitations upon my invention are intended other than are imposed by the scope of the appended claims.

What I claim as new and desire to secure by 6 Letters Patent of the United States is as follows:

1. Speed control mechanism comprising a frame structure, a shaft member mounted with respect to said frame structure and connectible with driving means, a train of gears driven by said shaft member, a driven shaft operated by said train of gears, centrifugal mechrotatably anism operated by said driven shaft, a brake controlled by said centrifugal mechanism under conditions of excessive speed of the driving means, and an auxiliary brake -operative under conditions of excessive'deceleration, of isaid drivlng means.

2. Speed control mechanism comprising a frame structure, a shaft member journaled with respect to said frame structure and connectible with driving means, a driven shaft journaled with respect to said frame structure, a gear train interconnecting said driven shaftV with said shaft member, and a pairY of braking devices disposed concentrically with respectto said driven shaft, one of said braking devices being operative to brake said driving means under conditions of excessive speed and the other of said braking devices operating to bring the driving means to a stop under conditions of excessive deceleration.

3. Speed control mechanism comprising a frame structure, a shaft member journaled with respect to said frame structure and connectible with driving means, a driven shaft journaled with respect to said frame structure, a gear train interconnecting said driven shaft with said shaft member, a centrifugal device operated by said driven shaft, a braking member operative under control of said centrifugal device under conditions of excessive speed of the revolving door, and a separate braking member concentrically disposed with respect to said driven shaft and operating to brake the revolving door under conditions of excessive deceleration.

4. Speed control mechanism comprising a frame structure, a shaft member journaled with respect to said frame structure and connectible with driving means, a driven Shaft journaled with respect to said frame structure, a gear train interconnecting said driven shaft with said shaft member, a centrifugal device operated by said driven shaft, a braking mechanism;Y operated by said centrifugal device for braking the revolving door under conditions of excessive speed, and a separate device operative byforce of momentum for braking the driving means under conditions of excessive deceleration.

5. Speed control mechanism for revolving doors comprising a driven shaft, means'for imparting rotation to said driven shaft in proportion to the rotary movement of the revolving door, centrifugal mechanism operated by said driven shaft, a braking device controlled by said centrifugal mechanism for bringing the revolving door to a safe speed and operative under conditions of excessive rotary speed, and separate means for bringing the revolving door to a stop and operative under conditions of excessive deceleration;

6. Speed control mechanism for revolving doors comprising a driven shaft, means for imparting rotation to said driven shaft in proportion to the rotary movement of the revolving door, centrifugal mechanism operated by said driven shaft, a braking device controlled by said centrifugal mechanism for bringing the revolving door to a safe speed and operative under conditions of excessive rotary speed, separate means for bringing the revolving door to a stop and operative under conditions of excessive deceleration, and means for predetermining the speed of rotation of said driven shaft at which said centrifugal mechanism becomes effective for braking the revolving door.

7. Speed 'control mechanism for revolving doors comprising a driven shaft, means'for imparting rotation to said driven shaft in proportion to the rotary Vmovement of the revolving door, centrifugal mechanism operated by said driven shaft, a, braking device controlled by said centrifugal mechanism for bringing the revolving door to a safe -speed and operative under conditions of excessive rotary speed, separate means for bringing the revolving door to a stop and operative under conditions of excessive deceleration, and an adjustable spring device operative for predetermining the speed of rotation of said driven shaft at which said centrifugal mechanism becomes effective for braking the revolving door.

8. Speed control mechanism comprising a rotary driving shaft, a driven shaft, a train of gears interconnecting said driven shaft with said rotary driving shaft, a friction wheel carried by said driven shaft, centrifugal mechanism operative with respect to said friction wheel under conditions of excessive speed for braking said rotary shaft, and an auxiliary braking device concentrically mounted with respect to said driven shaft and operative with said friction wheel in disengaged position for effectively stopping said rotary shaft under conditions of excessive deceleration.

9. Speed control mechanism for revolving doors comprising a casing, a master gear journaled in said casing, a driving shaft interconnecting said master gear with the rotary actuator of a revolving door, a gear train mounted in said casing and driven by said master gear, a driven shaft mounted in said casing and operated by said gear train, centrifugal mechanism and momentum mechanisin carried by said driven shaft, and a pair of braking devices disposed concentrically With respect to said driven shaft, one of said braking devices being operative under control of 'said centrifugal mechanism for retarding the rotation of the revolving door under conditions of excessive speed, and the other of said braking devices operative under control of said momentum mechanism to stop the rotation of the revolving door under conditions of excessive deceleration.

10. Speed control mechanism comprising a housing, a driving shaft and a driven shaft journaled with respect to said housing, a train of gears interconnecting said shafts, centrifugal mechanism mounted with respect to said driven shaft, a friction Wheel oatingly supported With respect to said driven shaft and operative under the control of said centrifugal mechanism for retarding the movement of the driving shaft under conditions of excessive speed, an auxiliary friction device mounted ooncentrically with respect to said driven shaft, and 'cam mechanism for shifting said auxiliary friction device into frictional engagement under conditions of excessive deceleration for bringing the said driving shaft to a stop.

11. Speed control mechanism comprising a driving shaft, a driven shaft, a housing for mounting said driving and driven shafts, a gear train interconnecting said shafts, said driven shaft having an axial recess therein for receiving a pair of coil springs, a block member disposed between said coil springs, a laterally extending rod member projecting through said block member and through diametrically opposite apertures in said driven shaft, a friction Wheel suspended on said laterally extending rod member, a centrifugal device operated by said driven shaft for shifting said friction Wheel into frictional engagement with a portion of said housing under conditions of excessive speed for retarding the rotation of said driving shaft.

12. Speed control mechanism comprising a driving shaft, a driven shaft, a housing for mounting said driving and driven shafts, a gear train interconnecting said shafts, said driven shaft' having an axial recess therein for receiving a pair of coil springs, a block member disposed between said coil springs, a laterally extending rod member projecting through said block member and through diametrically opposite apertures in said driven shaft, a friction wheel suspended on said laterally extending rod member, a centrifugal device operated by said driven shaft for shifting said friction wheel into frictional engagement With a portion of said housing under conditions of excessive speed for retarding the rotation of said driving shaft, and means for adjusting said coil springs for predetermining the speed at Which said centrifugal mechanism becomes effective to move said friction Wheel into engagement with the coacting portion of said housing.

13. Speed control mechanism comprising a driving shaft, a driven shaft, a housing for mounting said driving and driven shafts, a system of gears interconnecting said shafts, a carrier concentrically disposed about said driven shaft, centrifugally operated Weights mounted in said carrier, a friction Wheel concentrically disposed about said driven shaft and above said carrier, said friction Wheel being shiftable into friction engaging position With respect to said housing under conditions of displacement of said centrifugally operated weights for retarding the movement of said shaft upon excessive speed of the driving shaft, spring means for predetermining the speed at which said centrifugally operated weights become effective to displace said Afriction Wheel, and an auxiliary friction device disposed concentrically with respect to said driven shaft and effective under excessive deceleration of the driving shaft for bringing said shaft to a stop.

14. Speed control mechanism comprising a driving shaft, a driven shaft, a housing for mounting said shafts, means in said housing for transmitting rotary motion from said driving shaft to said driven shaft, a carrier disposed concentrically of said driven shaft, centrifugally operated Weights mounted in said carrier, a friction wheel extending laterally with respect to said carrier and shiftable with respect to said driven shaft in accordance with the variable displacement of said centrifugally operated weights, spring means for counterbalancing the mass of said friction Wheel with respect to the mass of said centrifugally operated Weights, means for adjusting the tension on said spring means from the exterior of said housing whereby said friction Wheel is adapted to be moved into frictional lengagement with a portion of said housing at a predetermined rotative speed of said driven shaft,

and a friction disc concentrically mounted with respect to said driven shaft and effective under conditions of excessive deceleration for bringing the driving shaft to a stop.

l5. In a speed control mechanism, a casing, a driving shaft and a driven shaft journaled along vertical axes with respect to said casing, means in said casing for transmitting motion from said driving shaft to said driven shaft, a laterally extending carrier concentrically mounted with respect to said driven shaft, a friction wheel extending directly over said carrier, spring means disposed within an axial recess in said driven shaft, a laterally projecting member extending through aligned apertures in said driven shaft and in said carrier for resiliently suspending said friction wheel with respect to said carrier and the spring means housed within said driven shaft, centrifugally displaceable weights in said carrier operative for shifting said friction wheel into engagement with a portion of said housing for retarding the driving shaft under conditions of excessive speed, and an auxiliary friction disc disposed concentrically of said driven shaft and operative under conditions of excessive deceleration for bringing the driving shaft to a stop.

16. In a speed control mechanism, a casing, a driving shaft and a driven shaft journaled along vertical axes with respect to said casing, means in said casing for transmitting motion from said driving shaft to said driven shaft, a laterally extending carrier concentrically mounted with respect to said driven shaft, a friction wheel extending directly over said carrier, spring means disposed within an axial recess in said driven shaft, a laterally projecting member extending through aligned apertures in said driven shaft and in said carrier for resiliently suspending said friction wheel with respect to said carrier and the spring means housed Within said driven shaft, centrifugally displaceable Weights in said carrier operative for shifting said friction Wheel into engagement with a portion of said housing for retarding the driving shaft under conditions of excessive speed, a plurality of cam faces on a portion of said carrier, an auxiliary friction disc having coacting cam faces, said cam faces being operative under conditions of excessive deceleration for forcing said auxiliary friction disc into frictional engagement with a different portion of said casing.

17. Speed control mechanism comprising centrifugally operated braking means for controlling the maximum running speed of a shaft; and separate, momentum operated, braking means for abruptly stopping the shaft under conditions of excessive deceleration; said braking means cooperating to effect safe operation of the shaft.

THURLOE M. HAGENBOOK.