US693877A - Portable fire-escape tower. - Google Patents

Description

6 Smets-sheet l.

.l o 9 I.. 57 2 ..D. e F.. .d e t n e t a P E A D c A M P. 7. 8, 3 9 6 0. N

PORTABLE FIRE vES'CPE TGWER.

(No Model.)

.- witnesses TH Noam vereis on.: PHoToLrrH. wAsMlNG'roN, D. CA

un. 693,877'. a v- Patented Febi 25, |902,A

P.mcnAx-:. PORTABLE FIRE ESGAPETOWER.

, (Application med annals, 1901.) (No MudelJ' SShoets-Shaet 2.

No. 693,877. Patented Feb. 25, y|302.

P. M'AGVRAE. PORTABLE FIBE ESCAPE TOWER. (Ammann-mea mums, 1901.-) (No Model.) 6 Sheete--Slieet 3.

A Patented F'eh-.\ 25,1902. P. MAcRAE.

PORTABLE FIRE ESCAPE TOWER.

(Application mea June 13,1901.)

(No Model.)

y @Morneys 'THE Nonms PETERS oq.. PHcTo-UTNOA. wAsHlNmoN. D. c.

No. 693,877. Patented Feb. 25,1902.

' P.MAcRAE.

PDRTABL'E FIRE ESCAPE lTLLWER.`

(Application tiled June 18, 1901.)

6 Sheets-Silent 5.

(No Model.)

Patented Feb. 25, |902.

- P. mums. PDRTABLE FIBETESGAPE TOWER.

' (Application tiled-June 13, 1901.)

6 Sheets-I-Sbeet 6.

(No Model.)

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feferzza Rd@ HVQNIOR UNITED gratins PATENT CFF-ICE.

PETER MACRAE, OFy ESCANABA, MICHIGAN.

`PORTABLE. FI RE1-ESCA'PE'TOWER.

SECEEICALIN fo'rril'ngl partuof Letters Patent No. 693,877, dated February 25, 19.0.2.

` Y Application filed June 13,1901. Serial No. 64,404. (No model.)

` To all whom t 711/614./ concern:

Be it known that I, PETER MACRAE, a citizen of the United Statesof America, residing at Escanaba, county of Delta, State of Michigan, have invented certain new and useful Imrovements in Portable Fire-Esca e Towers'- 9 and I do hereby declare that the following is a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use thesame.

My invent-ion relates to improvements in" portable fire-esca pe towers of that class which employ a lazy-tongs construction adapted to be folded compacily upon a wheeled truck.

One object of the invention is to provide a simple construction of lazy-tongs tower equipped with ladders which are foldablel and lowering of the tower being performed by or from a single prime shaft, which is driven in one direction only during the period when it is in service.

A further object is tol provide means operable from the single prime shaft for giving a shiftable adjustment to the lazy-tongs tower independent of the raising orlowering thereof, whereby the tower may be moved in a transverse direction, so as to assumea leaning position, and having its upper endlie close to a building while the truck may be stationed in the middle of the street.

A further object of the invention is to provide means for swinging the towerto different angular positions relative to the wheeled truck, such swinging mechanism being driven from the single prime shaft, so as to give the desired adjustment to the tower or to return it to normal position, and such mechanism being operable independently ofthe raising and lowering mechanism and of the towershifting mechanism.

A further object of theinvention is to provide an improved escape mechanism by which women, children, and men may be safely and quickly lowered from an elevated story to the ground, the escape cage or basket Vbeing raised for another load by motion derived through a train of gearing from the single prime shaft.

Further objects and advantages ot'` the invention will appear in the course of the subjoined description, and the novelty in the combination of mechanisms and in the construction and arrangement of parts `will be defined by the claims.

In the drawings hereto annexed, forminga part ofA this specitication,Figure 1 is a side elevation of my improved fire-escape tower, the dotted line illustrating the towerv raised to a position perpendicular to the base and the full lines representingtlle tower in a leaning position, the bed occupying a normal relation to the wheeled truck. Fig. 2 is a side elevation of the tower in the position shown f by dotted lines in Fig. l, except that the bed is shifted to a position at right angles to the wheeled truck. Fig. 3 is an enlarged plan `View of the apparatus with a portion of the' of the dotted line 6 6 on Fig. 3' looking in the direction of the arrow. Fig. 7 is avertical transverse section through a part ofthe shiftable bed, taken in the plane of the dotted line 7 7 on Fig. 4, looking in the direction of the arrow. Fig..8 is an enlargedk detail View, in

front elevation, of the drum associated with the cable for the fire-escape cage. Fig. 9 is a vertical* transverse section in the plane of the dotted line 9 9 on Fig. 4 looking in the direction of the arrow. Fig. 10 is a vertical crosssection in the plane of the dotted line l0 10 on Fig. 8, also looking in the direction of the arrow. Fig. V11 is la detail vertical section IOO . through the tubular shaft and the shit'table 'drawin designates the wheeled truck, having the axle 6, provided with the carrying-Wheels 7, whereby theapparatus is made portable. This truck is provided with the cross-rails 8 8, (see Fig. 4,) and the latter-mentioned cross-rail has the step-bearing 9, which is adapted to accommodate the lower end of the vertical shaft 13; The frame of the truck and the cross-rail 8 thereof have alined shaftbearings in which is journaled the horizontal prime shaft lO, the same being provided at its front end with the driving-pulley 11, which may be rotated 'by a belt from an engine or other source of power, although any suitable means may be provided for the operation of the shaft 10. The inner portion of this shaft is provided with a bevel-gear 12, which has interlneshing engagement with a similar bevel-gear 14, that is secured near the lower portion of said vertical shaft 13. (See Fig. at.)

15 designates the bed of the tower, thesame being provided with a central bearingplate 16. The wheeled truck has an annular metallic rack 17 secured to its upper side, and the central bearing-plate 16 of the bed 15 is arranged very close to the central portion of this annular rack, whereby the bearing-balls 21 may be interposed between the central portion of the annular rack and the bearingplate 1G, so that the bed may be turned upon the wheeled truck. The vertical shaft 13 passes loosely through the central portion of the annular rack 17, the center of the bearing-plate 16, and the framework of the shiftable bed 15, the upper end of said vertical shaft being journaled in a suitable bearing-plate 13, secured to the upper side of the bed, and this shaft 13 is adapted to serve as the axis on which thebed 15 maybe turned in a horizontal plane, and said shaft also serves to transmit the motion of the prime shaft 10 to the horizontal counter-shaft 22. `The annular fixed rack 17 is provided with the internal gear-teeth 18, and to said rack 17 is fastened the fixed gear 19, the lat- 1er having `the teeth 20 on its external periphery. The gear-teeth of the annular rack 17 and of the xed gear l19 are practically in opposing relation, so that a gear 64 of an adjusting-shaft (53 may be made to mesh either with the rack 17 or with the xed gear 19 for the purpose of changing the relation of the bed `to the wheeled truck, all as will be hereinafter more fully described. The countershaft 22 is arranged in a horizontal position above the prime shaft 10, and it is mounted insuitable bearings 23, which are provided on the bed, whereby the `counter-shaft is mounted on' and is shiftable with the bed. The rear portion of the counter-shaft is provided with a bevel-gear 2l, which has intermeshing engagement with a similar bevelgear 14, secured to the upper portion of the vertical central shaft 13, and the front portion of said counter-shaft 22 is provided with anotherbevel gear-wheel 2i. It will be noted that the shaft 13 transmits the motion of the prime shaft 10'to the counter-shaft 22 and that the gears 14: 24. of the shafts 13 22 remain in mesh with each other at all points in the adjustment of the bed 15 upon the wheeled base 5.

designates a horizontal transverse shaft which is arranged at the front portion of the shiftable bed 15 and is journaled in suitable bearings 26, said transverse shaft lying at right angles to the v counter-shaft 22 and being shiftable with the bed 15, so as to always maintain its operative relation to said counter-shaft and to the worm-shafts, which will be presently described. Said transverse shaft 25 is provided with a bevel-gear 27, that has intermeshing engagement with the bevelgear 24 on the counter-shaft `22, and the transverse shaft 25 is furthermore provided with two sets of bevel-gears, one set of which is indicated at 28 28L and the other set at 29 29% (See Fig. 3.) All thesegears are made fast with the shaft, so as to rotate therewith, and the gears of each set are disposed in opposing relation, so that they will face each other.

31 designate the worm-shafts, the same being arranged in horizontal positions on opposite sides of the counter-shaft 22 and journaled in proper bearings on the bed 15, so as to occupya shiftable relation to the sets of opposing gears on the transverse shaft 25, each wormshaft having means associated therewith so as to change its relation to the set 0f bevel-gears independently of the other worm-shaft. The worm-shaft 30 is provided at its front portion with a bevel-gear 30, which is adapted to be shifted into intermeshing engagement with either the bevel- gear 28 or 28, and in like manner the other worm-shaft is provided with a bevel-gear 3l, which may be adjusted to mesh with either of the gears 29 or 29. The front portion of each worm-shaft being shiftable with relation to one set of the bevelgears, I` have provided means for supporting the rear portion of said shaft in a manner to permit of its shiftable adjustment, and this is attained by the employment of a rounded head 32, which is loosely Iitted in a socket or cavity 33, which is provided on the bed 15. (See Fig. 6.) The front portion of each shaft 30 and 31 is journaled in a shiftable bearing 34, which is constructed to engage with a guideway on the cross-bar 3(5,the latter being secured to the framework of thebed 15. (SeeFigs-6and7.) Theadjustmentofthisslidable bearing 34 and the front portion of each worm-shaft is effected by a lever37, which is fulerurned at 38 on a cross-bar 39, provided on the framework of the bed, and the lower portion of this adjusting-lever 37 is connected operatively with the slidable shaft-bear- IOO IIO

ing 34 by a link 40. The lever is held in its adj usted position by a latch 41, that is mounted on the lever and is arranged to engage with a notched segment 42, which is secured on the cross-bar 39 of the bed15. Each wormshaft is adapted to be shifted by its lever 37 to either of three positions-to wit., when the lever is thrown over to the right in Fig. 7 the bearing 34 and the worm-shaft 30 are shifted to the left, so that the bevel-gear on said worm-shaft will have intermeshing engagement with one of the opposing bevelgears on the transverse shaft 25. Byreversing the position of the lever 37 or moving it to the left in Fig. 7 the bearing 34 and the front portion ot' the worm-shaft are shifted to the right in order that the bevel-gear on said worm-shaft may have intermeshing engagement with the other bevel-gear of the set on the transverse shaft 25; but when the lever 37 is adjusted to a vertical position, as

shown by Fig. 7, the slidable'bearing and the front portion of the worm-shaft are positioned midway between the opposing bevelgears of the set, thus throwing the wormshaft bevelgear out of engagement with either of the opposing bevel-gears.

The worm-shafts 3031 are provided near their rear ends with the worms 43 44, respec tively, and said worms are arranged to intermesh with the worm-gears 45 46, which are.

loosely mounted near the lopposite end portions of a pivotal shaft 47, the latter being mounted in suitable bearings 47 7, provided on the framework of the shiftable bed near the middle portion thereof. Each of the. shafts being shiftable independently of the other:

worm-shaft by proper adjustment of the lever 37 ,it is evident that the two worm-shafts may be driven simultaneously in the same direction in order to turn the worm-gears 45 46 in the same direction; or one worm-shaft may be thrown out of operation and the other worm- -shaft may remain in service and in engagement with one of the set of bevelgears,so as to operate one of the worm-gears 45 46, for a purpose which will hereinafter be described. The pivotal shaft 47 serves to support the weight of the tower, which is of thelazy-tongs construction shown by the drawings, and in view of this fact it is necessary to make said shaft 47 quite substantial in construction.v

48 48L 48b designate one set of the tower members or links, which are made fast one with the other and with the worm-gear 45, because the member 48 is secured rigidly to said worm-gear 45,and all of the members or links 48 48a 48b are united solidly together by a cross-bar 48,all of said members or links having their inner portions fitted loosely on the pivotal shaft47 The other set of links or tower l members 49, 49, and 49b are made fast with the other worm-gear 46 and with each other because the member 49 is secured firmly to the worm-gear 46,.and the members 49"L 49b are joined rmly to each other and to the member 49 by anothercross-bar 49e, all of the construction is continuous throughout the height ofthe tower in order to make the latter extensible to the desired height.

I prefer to equip thellazy-tongs towerwith a seriesof ladders, (indicated by the numerals 54 55,),as represented more clearly by Fig. 2. Each ladderl 54 extends parallel with the links 48 50, while the other ladders areparallelt to the links or members 5l. Each ladder has one end attached or connected in a suitable way toone of the cross-rods 53,. while its other end rests upon the other cross-rod, and the ladders provide means wherebya fireman may ascender descend the tower in a zigzag path. The upper portion of the tower is equipped with an auxiliary lladder 56, which is pivotally connected at ,57 to thezupper members 51 Vof the tower, and 'this ladder is adapted to be adj usted beyond the toWer,- as representedV by Fig. 1, or it may be folded over upon` the tower, as shown by Fig. 4`

l will now proceedto describethe Ameans by which the shiftable bed 15 may be adjusted across the wheeled truck or back to its normal position. Y

59 designatesa slidable carriage which is arranged in a horizontall position between two of the rails of the bed-frame 15, and said carriage is provided inits sideedges with the grooves 60, the same adapted to receive-the guide-ribs 6l, which are made fast with lthe -IOO frame-of the shiftable bed, as more clearly a vertical adjusting-shaft 63, the lowerv portion of which is provided with a spur-gear64,4 while the upper portion is equiped with a bevel-gear 65. (See Fig.'4.) l 64 of said shaft is arranged between the internally-toothed rack 17 and the fixedv gear 19 and according to the position of the4 carriage 59, and this gear 64 is adapted to mesh with the fixed gear 19 orwith the rack 17.

The spur-gear The adjusting-,shaft 63 is adapted to be driven I from the counter-shaft 22, which, it will be recalled, is driven by the shaft 13 from theprime shaft 10, 'and to accomplish this endl' provide the slidable carriage :59with an upstanding arm 66, which' is constructed with a bearing 67, that is sleeved on the countershaft 22. The counter-shaft 22 is provided -contained parts may easily"y be effected .j usting-shaft 63.

cured to the bed-frame.

with a longitudinal key or feather 68, and in the bearing 67 is loosely fitted a tubular shaft 69a, the same having a groove which receives the `feather GS, and said tubular shaft is furthermore provided with a bevel-gear 69, that is arranged to have intermeshing engagement with the bevel-gear 65 on the vertical ad- It will be observed that the shaft 63 and its two gears are adjustable with the carriage and that the tubular shaft (39, with the gear 69, is also adjustable with the carriage;` but the tubular shaft and its gear being splined to the counter-shaft the motion of the latter will be transmitted by the gears (i9 and 65 to the adjusting-shaft 63 at all points of its adjustment, whereby the gearing will transmit the motion of the counter'- 4shaft 22 to the pinion 64 when itis desired to shift the position of the bed.

The adjustment of the carriage 59 and its through the medium of a lever 70, which is yfulcrumed at a point intermediate of its length on a stud of aplate 71, that is fixed to a portion of the framework ofthe shift- .able bed. The lower portion of this lever is `connected by a link 72 to the carriage, and `the upper portion of said lever is equipped lwith a latch 73, arranged to have engagement with a notched segment 74, which is se- By moving thelever in one direction the carriage will be adjusted to make the gear 64 intermesh with the fixed gear 19, and tho motion of the shaft 22 will .cause the bed to swing or turn in one direc- `tion around the axis aifordedby the vertical shaft 13, whereby the entire bed 15 and the extensible tower may be adj usted to a position at right angles to the length of the wheeled truck, as shown by Fig. 2. A reversal of the lever 70, however, will draw the `carriage in an opposite direction and `make `the gear 64 mesh with the internally-toothed rack 17, and the described train of gearing transmitsthe motion of the counter-shaft 22 to the pinion 64 for the purpose of swinging the bed 15back to its normal alined relation to the truck 5. Of course the carriage 59 may` be adjusted in a position which places the pinion 64 free from engagement with the rack 17 and the gear 19, thus allowing the bed 15 to remain at rest.

JIt. is` desired to provide means which will Alock the shiftable bedin its adjusted position, so as to maintain it steadily in place, and as one` means for accomplishing this end I have equipped` the bed 15 with the locking-posts 75 .75, the same arranged at the rear corners of vposts 75 75 firmly into engagement with the ground, whereby said posts serve to steady the bed in its adjusted positions.

With the apparatus I have associated iireescape devices adapted to quickly and safely transport a person from an upper story of a burning building to the ground, and these devices are operable independently of the other services for which the apparatus is designed. I employ an escape-cable 82, which is guided by suitable sheaves 83 S4 at the front and rear upper portions of the tower, one end of this cable being connected to a suitable basket or cage S5. The otherend of the cable is coiled around a drum 8(5,that is loosely mounted on a shaft 87, so as to be free to slide endwise thereon and to rotate on its axis. This shaft is journaled in suitable bearings S8, provided on the frame of the shiftable bed, as shown more clearly by Fig. S, and to the shaft is secured a gear-pinion 89, which has intermeshing engagement with aspur-gear 90, that is made fast with the transverse shaft 25, (see Figs. 3 and 4,) whereby the drum-shaft may be driven by-motion derived from said transverse shaft 25. This shaft 87 is also provided witha fastclutch member 91, that is in opposing relation to a shiftable clutch member 92, which is provided on the drum S6, and this drum is provided at its opposite end portion with a groove 93, that is arranged to receive the pins 94a of a shipper-lever 94, the latter being fulcru med to the framework of the bed and having its handle end disposed in convenient position, as shown more clearly by Fig. 3. The drum is furthermore provided with a brake-surface 9G, which is partially enpermit the basket and its load to descend by gravity, and thereby draw on the cable 82, so as to uncoil said cable from the drum. After the load is discharged from the basket or cage the brake is released and the lever 94 is adjusted in a direction to move the drum 86 to a position wherein the clutch member 92 will engage with the clutch member 91. The

drum is thus made fast with the shaft, and Vthe latter is rotated through the gears S9 90, whereby the cable 82 may be coiled on the drum, so as to raise the cage or basket into position to receive another load.

The operation of the apparatus may bc sum- ICO IIO

mal-ized as follows: With the drum-shaft 10 constantly rotating in one direction it is necessary to shift the levers 37 to the positions indicated in Fig. 2 when it is desired to raise the tower to a vertical position, which is indicated by dotted lines in Fig. l. The adjustment of the levers 37 to the prescribed positions moves the shafts 30 3l, so thatl the gears 30a and .Sla will-have intermeshing engagement with the gears 28 and 29, whereby theA shafts 30 81 will both be brought into service for rotation in a common direction and adapted to drive the two worm-gears 45 46 with equal angularvelocity. These wormgears will be turned in corresponding directions and impart motion to the lazy-tongs tower, whereby the latter will be extended or unfolded in a plane perpendicular to the shiftable bed l5 and as represented by dotted lines in Figl; To lower the tower toits folded compact position upon the truck, (shown by Fig. 4,) the levers 37 are adjusted in order to reverse the positionsof the shafts 30 3l and make the bevel-gears ()n 31W have intermeshing engagement with the gears 28L 29iL on the transverse shaft, whereby the two worm-shafts will be simultaneously rotated in the reverse direction, so as to impart like motion, and with equal angular velocity, to the worm-gears. One advantage'of the wormgear between the shafts 30 3l and the lower elements of the toweris that the parts of the tower will be locked in position, which is especially advantageous whenthe tower is extended or adjusted for service, because the worm-gearing dispenses with separate locking mechanism. If the tower is raised to its vertical position and it" is desired to'give a leaning appearance thereto in a direction to-` ward the rear part of the apparatus, as shown by full lines in Fig. l, theV worm-shaft 3l is adjusted for its bevel-gear l3la to lie between and out of mesh with the set of bevel-gears 29 29h-whereas the other worm-shaft 30 is adjusted so as to make its bevel-gear 30a engage with the bevel-gear 28. The motion of the transverse shaft 25 is thus transmitted, Ithrough the gears 2S 30a, to the shaft 30, which turns one worm-gear 45 of the two worm-gears 45 46 on the pivotal shaft, and thus the members 48 48 48h of the tower will be raised and the other parts of the tower will be shifted, so as tov make the structure assume the leaning position represented by Fig. l. To bring thetower back to its vertical position, it is necessary to reverse the worm-shaft 30 in a direction to bring its gear 30a into mesh with the other gear 28 of the set of opposing bevel-gears on the transverse shaft, and thus the tower may be given the leaning adjustment or brought back to nor'- mal position byv motion derived from the prime shaft. f

The position of the bed l5 on the truck may be changed either when the tower is in its unfolded position orin its extended position,

v is moved in an opposite direction and the 'gear 64 mesheswith the rack 17.

The locking-posts '75a may be brought into service when the bed is shifted to its transverse position, and the escape-cage and its cable may `also be employed at any period in the adjustment or service of the tower except when the latter is folded.

Changes within the scope of the appended i claims may be made inthe form and proportion of some of the parts while their essential features are retained and the spirit of the invention is embodied. Hence I do not desire to be limited to the precise f orm of all the parts as shown, reserving the right tovary therefrom. n

Having thus described my invention,what I claim as new is l. In an apparatus of the class described, the combination with a lazy-tongs tower,of a pivotal shaft on which the lower members of the tower are mounted, gear elements secured fast to dilferent sets of the tower members vand adapted to independently or simultaneously actuate the same, adjusting-shafts operatively connected with said gear elements, a single transverse shaft disposed adjacent to said adjusting-shafts and provided with sets of facing gears adapted to mesh separately with gears on the adjusting-shafts, means for rotating the transverse shaftin one direction, and means for individually shifting the adjusting-shafts into meshing relation to either of the sets ofr gears on the trans-l verse shaft, as and for the purposes described. j

2. In an apparatus of the class described, the combination of a wheeled truck, a bed shiftably mounted thereon, a lazy-ton gs tower supported by the bed, a prime shaft mounted on the truck, a transverse shaft'and a coun.-`

.ter-shaft mounted on the bed and driven'from the prime shaft, shiftable toweradjusting.

shafts mounted on the bed and adapted to be driven individually or collectively from the transverse shaft for raising, lowering or inclining the tower by motion derived from the prime shaft, andb'ed-adjusting devices having means geared tothe connter-shaftand to the truck for swinging the bed audits contained tower on a vertical axis, substantially as described. y

3. In an apparatus of the class described,

the combination of a pivotal shaft, the wormgears loosely mounted thereon, a lazy-tongsy tower having its lower members loosely mounted on the pivotal shaft vand with the different sets of lower members made fast with the worm-gears individually, the worm.- shafts loosely supported at one end and'operatively connected with the worm-gears, a transverse shaft provided with different sets of facingbevel-gears, and 'means forshiiftably IOC IIO

supporting the free ends of the worm-shafts with relation to said facing sets of bevelgears, substantially as described.

4. In an apparatus of the class described, the combination of a pivotal shaft, Wormgears individually mounted thereon, a tower having its lowermembers made fast with the worm-gears respectively, a transverse shaft provided with sets of facing gears, cross-bars adjacent to the transverse shaft, shaft-bearings slidably mounted on the cross-bars and having suitable means for individuallj)T 0perating the same, worm-shafts loosely supported at one end, journaled at their other ends in the shif table shaft-bearings and having interln eshing engagement with the wormgears, and bevel-gearsv on the worm-shafts and arranged to be engaged with either bevelgears of the sets and to be free from engagement therewith, substantially as described.

5. In an apparatus of the class described, the combination of a wheeled truck, a shiftable bed thereon, a prime shaft carried by the truck, a lazy-tongs tower mounted on the bed, the transverse shaft on the bed, the shiftable worm-shafts mounted on the bed and geared to worm-gears on the tower-sections and adapted to be driven by the transverse shaft, a counter-shaft geared to the transverse shaft and to the prime shaft, opposing gears mounted on the truck and a shiftable carriage, and a shaft journaled in the carriage and driven from the counter-shaft and adapted to engage with either of said opposing gears, substantially as described.

(i. In an apparatus of the class described, the combination of a wheeled truck, a bed `shiftable thereon, a tower supported by the bed, a prime shaft, a vertical shaft geared to the prime shaft, a counter-shaft driven from the vertical shaft, the fixed gear and the anuular rack supported by the wheeled truck, a

the` combination of a Wheeled truck, a shiftl able bed mounted thereon and carrying a tower, a fixed gear on the truck, an internally-toothed rack fixed to the truck, a slidable carriage on the bed, a shaft mounted in the carriage and having a gear arranged to mesh either with the fixed gear or with the annular rack, means for adjusting the'carriage, and means for rotating the shaft in thecarriage, substantially as described.

8. In an apparatus of the class described, the combination of a wheeled truck, a shiftable bed thereon, a fixed gear on the truck, an internally-toothedrack fixed to the truck, a counter-shaft mounted on the bed and provided with a spline, a tubular shaft engaging with the counter-shaft and its spline and having a bevel-gear, a carriage slidably fitted on the bed and provided with two bearings, one of which supports the tubular shaft, an adjusting-shaft mounted in the carriage and having a bevel-gear which intermeshes with the first-named bevel-.gear and provided with a spur-gear arranged to engage either with the rack or with the fixed gear, a lever connected with the carriage, and means for rotating the counter-shaft, substantially as described.

In witness whereof I have hereunto set my hand in the presence of two witnesses.

PETER MACRAE.

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