US2905272A - Power-operated mobile hoists - Google Patents

Description

Sept. '22, 1959 R. T. LUNN POWER-OPERATED MOBILE HOISTS 5 SheetsSheet -1 Filed May 20. 1955 In uentor A ttorneys POWER-OPERATED MOBILE HOISTS Filed May 20 1955 5 Sheets-Sheet 2 @7 2o F/G. 2.

- Inventor A-b-uu a K W2 A ttorneys Sept. 22, 1959 R, T, L NN j 2,905,272

POWER-OPERATED MOBILE HOISTS Filed May 20. 1955 I 5 Sheets-Sheet 3 In ventor Mud/TQM S By MLW Attorneys Sept. 22, 1959 R. T. LUNN POWER-OPERATED MOBILE HOISTS' 5 Sheets-Sheet 4 Filed May 20. 1955 Inventor By In KW,

Attorneys Sept. 22, 1959 R. T. LUNN POWER-OPERATED MOBILE HOISTS 5 Sheets-Sheet 5 Filed May 20. 1955 MLW Attorneys Patented Sept. 22, 1959 POWER-OPERATED MOBILE HoIsTs Richard T.v Lunn, London, England, assignor to A.C.E.

Machinery Limited, London, England, a British com- F Application Ma 20, 1955, Serial No. 509,778

Claims priority, application Great Britain September 2, 1954 Claims. (Cl. 18711) This. invention relates to power operated mobile hoists of the kind comprising a vertical mast or tower upon one side of which a guided platform, adapted to carry loads of comparatively low density, is elevated by means of a winch situated adjacent the base of the said mast.

Hoists of this character are particularly suited for employment on building sites or for handling loads to and from the freight loading hatches of aircraft, railway rollin-g stock and the like.

Such apparatus as constructed hitherto to raise loads to considerable heights have been heavy and unwieldy in operation and have therefore required the employment of several operators to effect their safe transit to, and subsequent manoeuvring and erection upon, a chosen site and have proved unstable in operation when erected on an uneven surface.

It is therefore a primary object of the present invention to provide a power operated mobile hoist of light and economical construction which may be manoeuvred and erected by a single operator upon an uneven surface and which will remain stable under adverse working conditions.

A further object of the invention is to provide improvements applicable to hoists of the general character above described, such improvements being designed to render suchapparatus safer' during operation, to prevent over-elevationof the load supporting members and to prevent interference with thewinch controlling means by unauthorised persons.

According to the invention a power operated mobile hoist having a tower angularly displaceable from; a substantially horizontal travelling positioninto a vertical working position is characterised by means to facilitate the erecting and lowering of the tower assembly comprising arcuate members forming part of the tower supporting structure in offsetrelationship to the vertical projection of the centre of gravity of the hoist upon the ground" surface, each arcuate member having aground engaging surface upon which the hoist may be swung into, or away from, its working position, and the Winding drum and power unit being mounted uponachassis frame pivotally connected to the said tower supporting structure'and provided with at least one pair of road wheels adapted to' support the hoist during transit and to be raised from the ground surface by; the erection of the said, tower.

Reference will now be made to the accompanying drawingswhich show a power operated mobile hoist const-ructed' according; to the invention and in which:

Fig. I is aside elevation,

Fig. 2 is. a front elevation,

Fig; 3' is a-plarr,

Fig: 4" is aside elevation of the hoist in its travelling position,

Fig. 5 is an elevation par-tly'in section ofthe carriage unit;

Fig; 6 is a sectional elevation: of the platform lifting mechanism,

Fig. 7' is an elevation of the winch controlling means,

Fig. 8 is a side elevation showing the power drive to the winch;

Fig. 9 is a sectional View taken through the winding drum and the eccentric adjusting means therefor;

Fig. 10 is an elevation partly in section of the safety means to prevent falling of the platform from anelevated position; and

Fig. 11 is a plan view of the safety means. 7

In the construction illustrated the hoist comprises a tower 1 supported upon a base structure 2 to which apower driven winch unit indicated generally at 3 is pivotally connected. The tower 1 is of open lattice or Warren girder construction and the forwardly facing longitudinals 4 thereof constitute guide rails for the pairs of rollers 5 and 6 arranged on opposite sides of the rail flanges and rotatably carried by the load lifting platform 7 as shown in Fig. 6'. A retaining bracket 8 is provided to prevent outward movement of the lower end of the platform when unladen or in transit.

The winch unit 3' comprises a prime mover 61 (prefer ably an internal combustion motor) which transmits power through chain and sprocket gearing 62 to a friction pinion 63' (Fig. 8). The winding drum 10* of the winch is mounted in eccentric bearings- 11 (Figs. 7 and 9) carried in the winch frame 64 and the drum is provided with a flanged rim I2 adapted to be engaged fric tionally by the pinion 63. A hand operated arm 13 is provided for adjusting the position of the eccentric bearings to bring the rim 12 into or out of driving contact with the pinion 63. The arm 13 is provided with a counterbalance weight which operates by gravity, when released, to move the eccentric hearings to a position in which the flanged rim 12 is disengaged from the pinion 63 and engaged by a brake shoe 15'. Consequently, winding and lifting of the load can only be effected when the" operator lifts the arm 13.

Raising and lowering of the load lifting platform 7' is effected by the lifting cable 16 which inthe interest of accessibility and in order to maintain an even distribution of load about the longitudinal axis of the mast is arranged on the outside of the mast structure and guided by the pulley l7 and the pulleys 1% and 19 arranged in tandem in the head-gear 2h. As shown in Figs. 2 and 3 the head-gear 20 is inclined with respect to the mast axis to ensure a substantially vertical fall of the lifting cable which is passed beneath the platform pulley 21 and se curedto the masthead.

Safety means (Figs. 10 and 11) are associated with the pulley 21 to prevent a free fall of the platform from an elevated position and comprise a pair of toothed eccentric members 37 secured one to' each end of a shaft 65 carried in bearings provided in the block 38' which also supports the axle of the rollers 5'. The unitary structure achieved by the employment of the block 38 ensures that the necessary spaced relationship between the rollers 5 and the cam members 37 is unaffected by wear of the surfaces of the" guide rails 4; The cam shaft 65 is connected' by means of an articulated link 3'6 to a push rod 35- passed axially through a" coil spring 39 and abutting at its free end against the pulley cage 66'. Limited vertical movement is permitted to this cage and during normal operation, the resistance offered to the lifting cable 1'6 by the platform, whether laden or unladen, is suflici'ent to displace the said' push-rod 35 against the spring 39 and partially rot-ate the shaft and the earns 37 to a position in which the. smooth. areas of the cam surfaces are adjacent the surfaces of the guide rails 4.

In the eventoffailure of the lifting cable, the cessation of the upward force normally exerted upon the pulley 21- permits this member and the push rod' 35 todescend under gravity and with the assistance of the spring 39. The cams 37 are thus partially rotated to an operative position in which their serrated surfaces engage the surfaces of the guide rails 4 and the rolling action imparted to the cams during the initial stage of the platform descent serves to force the cams into engagement with tne surfaces of the rails, thereby braking and arresting the platform while its velocity is comparatively low.

Means are provided to prevent overwinding of the lifting cable 16 and these means, which are shown in Fig. 7, comprise a trip wire 23 secured at one nd to the head of the tower at 67 (Fig. 2) and at its other end to a spring biassed tension maintaining bolt 27 mounted on a horizontal component of the tower structure. The Wire 23 passes around a guide pulley 26 at the base of the structure and that portion extending between the guide pulley and the bolt 27 cooperates with an articulated link 63 carried by a latch member 29 pivotally connected to the free end of the arm 13, which operates the eccentric bearing 11. Movement of the arm 13 is effected by operation of a pull rope 9 connected to a secondary lever 33 and passing over a pulley 69 carried by the tower 4, the other end of the pull rope being provided with a hand grip 7h. The secondary lever 33 is pivotally mounted at 40 and terminates in a striking bar 32 adapted to engage a recess 31 formed in the curved surface of the latch member 29. A stop member 41 (Fig. 2) is located on the trip wire 23 at a predetermined distance below the tower head and is adapted to cooperate with an eye 25 extending from the platform 7 and embracing the trip wire 23. In the operation of this stop mechanism the contact of the eye with the stop member 41 when the platform 7 reaches the utmost limit of its travel, as shown in Fig. 12, causes a pull to be exerted on the trip wire 23, thereby tending to straighten that portion of the wire which lies between the puliey 26 and the bolt 27, and the resulting angular movement of the latch member 29 disengages the recess 31 from the striking bar 32. This operation frees the control arm 13 to descend by gravity, partially rotate the eccentric bushing 11 and move the flange 12 of the winding drum into engagement with the braking means 15, thereby preventing further movement of the platform 7.

Should the operator maintain a force on the pull rope 9 when the latch mechanism has been released, the secondary member 33 will assume a position in which an adjustable stop bolt 42 engages a fixed abutment member 43, and in this condition the limited purchase available to lift the arm 13 prevents this arm from assuming the position in which the winch drive is engaged but allows the platform 7 to be lowered. The latch member 29 is returned to its operative position shown in Fig. 7 by a spring 44 when lowering of the platform 7 relaxes the tension on the trip wire 23 and the secondary member 33 is restored to the position shown on release of the trip wire 23 to its latched position.

Selectively operable locking means are provided to prevent unauthorised manipulation of the winch control and comprise a lockable member 45, which may conveniently be constructed in the manner of a key operated padlock, l aving a slidable hasp 46 adapted to be passed through the staple 47 secured to the lower surface of the control member 13. The member 13 and the eccentric bearing 11 may thus be retained in a position in which the flange 12 of the winch drum and the braking means 15 are frictionally engaged thereby preventing movement of the platform. When disengaged the hasp 46 is swung downwardly about the axis of its lowermost leg to permit unimpeded movement of the member 13.

When the hoist is erected in the operative condition hereinbefore described its vertical disposition is maintained by the screw jacks 48 and the pads 49 secured one to each end of the arms 50 which are pivotally connected to the base structure 2 and angularly adjusted by the screwed members 51.

In lowering the hoist into its travelling position the screw jacks 48 are each fully retracted to lower the under surfaces of the arcuate members 52 into engagement with the ground and the tower is tilted to roll or swing about the arcuate ground-engaging surfaces toward the travelling position shown in Fig. 4. During the initial stage of the angular displacement of the tower the winch and power unit provide a counter-weight and enable the operation to be exercised by a single operator employing the leverage offered by the lowered platform.

As this displacement increases, the road wheels 60 engage the ground surface and the winch chassis pivots about a connection comprising pins 53 projecting from the chassis engaging slots 59 formed in members 71 forming fixed parts of the tower structure. The reduction in counterweight thus effected and the balance struck between the upper tower section and the platform while supported solely by the arcuate members 52 permits the tower to be manually lowered in a substantially balanced condition into engagement with a rest bar 55 carried by the winch chassis.

Referring to Fig. 5 it will be seen that a member 55 to which the rest bar 55 is attached comprises two coaxial telescopic members, the uppermost of which is permitted sliding movement against a compression spring 57. The tower 1 is thereby protected against sudden deceleration and subsequent damage as a result of mishandling during the lowering sequence and during transportation the winch chassis and the members 56 pivoting about 53 act in the manner of a swinging arm suspension system to insulate the tower against shocks created when travelling o-ver uneven surfaces.

To restrain the platform 7 against undesired movement during lowering operation and while travelling, a hook 58 is provided which is secured at one end to the trip wire tension bolt 27 and can be moved by hand around the trip wire slightly above the eye 25 This prevents sliding movement of the platform when the hoist is in the travelling position shown in Fig. 4, and until the hook is disconnected from the trip wire and returned to the position shown in Fig. 7, the platform 7 cannot be raised.

Erection of the hoist into its working position is obtained by reversing the sequence of the operations above described, and the erection upon an unprepared or inclined site is facilitated by articulated connection of the winch chassis to the base structure 2 by means of the pins 53 and slots 59.

I claim:

1. A power operated mobile hoist comprising a tower, means for displacing said tower from a substantially horizontal travelling position to an erected working position,

1 a mobile chassis frame pivotally connected directly to said tower and providing a supporting structure therefor in both of said positions, arcuate members forming parts of said supporting structure and arranged in offset relation to the vertical projection of the center of gravity of the tower, a ground engaging surface on each arcuate member upon which the tower is swung to and from its erected working position, a winding drum and power unit mounted upon said chassis frame, a mobile platform on said tower, a cable connecting said platform to said winding drum, at least one pair of road wheels supporting the hoist during transit and which are raised automatically from the ground by the erection of said tower, means for protecting said tower against shock when lowering and when traversing uneven ground comprising resilient members extending angularly from said mobile chassis, and a transverse bridging member upon which the tower is adapted to rest when lowered.

2. A power operated mobile hoist having a pair of road wheels and comprising a chassis movable about the axis of the road wheels, a tower pivotally connected to said chassis and movable relatively thereto between an operative and an inoperative position, a power and winding gear unit mounted on said chassis, a platform movable vertically on said tower and connected to said winding gear, arcuate shoes forming parts of the tower structure and movably connected to said chassis and upon which shoes the tower is swingable during its movement between its inoperative and operative positions, a brake shoe for said winding gear, a weighted control member for said brake shoe and the power operation of said winding gear, and means to automatically interrupt the power drive of said winding gear and to apply the brake shoe to the winding gear upon elevation of the platform to a predetermined height comprising a trip wire extending longitudinally of the tower and provided with an adjustable stop adapted to cooperate with an abutment carried by the platform, and releasable latch means operatively connected to the trip wire and operative in response to an increase in trip wire tension to allow the weighted control member to descend to a position in which the winding gear is disengaged from its power drive and engaged with the brake shoe.

3. A power operated mobile hoist as defined in claim 1, including guide rails for said platform on one side of said tower along which said platform is displaceable, and means for preventing free fall of said platform comprising a shaft carried by said platform, and at least one pair of toothed eccentric members mounted on said shaft and partially rotatable into frictional engagement with said guide rails upon cessation of an upward force normally exerted on the platform by the winding gear for locking the platform against movement.

4. A power operated mobile hoist as defined in claim 2, including a winch frame, and means to prevent unauthorized operation of the winding gear comprising releasable locking means secured to the winch frame and engageable with said weighted control member to retain said member in its lowered position.

5. A power operated mobile hoist having a pair of road wheels and comprising a chassis movable about the axis of the road wheels, a tower pivotally connected to said chassis and movable relatively thereto between an operative and an inoperative position, a power and winding gear unit mounted on said chassis, a platform movable vertically on said tower and connected to said winding gear, arcuate shoes forming parts of the tower structure and movably connected to said chassis and upon which shoes the tower is swingable during its movement between its inoperative and operative positions, and means to protect the tower against shock when lowering and when traversing uneven ground comprising resilient members extending angularly from said chassis and a transverse bridging member upon which the tower is supported and adapted to rest in lowered position on said chassis.

References Cited in the file of this patent UNITED STATES PATENTS 2,107,956 Olsvary Feb. 8, 1938 2,490,198 Boone Dec. 6, 1949 2,671,530 White Mar. 9, 1954 2,708,039 Le Tourneau May 10, 1955 FOREIGN PATENTS 256,660 Great Britain July 26, 1926 505,636 Great Britain May 15, 1939 676,191 Great Britain July 23, 1952 1,012,261 France Apr. 9, 1952 1,078,983 France May 19, 1954

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