US 2903896 A
Description (OCR text may contain errors)
Sept. 15, 1959 F. E. GREENE 2,903,896
PLATFORM HOISTS Filed Feb. 28, l1955 3. Sheets-Sheet 1 zal Sept 15,' 1959 F. E. GREENE 2,903,896
PLATFORM HoIsTs Filed Feb. 28. 1955- 3 Sheets-Sheet 2 irraP/vi/ Sept. 15, 1959 F. E. GREENE 2,903,896
PLATFORM HorvsTs Filed Feb. 28, 1955 .'5 Sheets-Sheet 3 an o PLATFORM HOISTS Fred E. Greene, deceased, late of Coloma, Calif., by Cora S. Greene, administratrix, Sacramento, Calif.
Application February 28, 1955, Serial No. 490,952
2 Claims. (Cl. 74-95) The invention relates to improvements in devices for raising and lowering materiel and personnel and, more particularly, to devices for raising `and holding temporarily in place building materials, such as plaster board, used in the construction of houses and other buildings.
It is an object of the invention to provide a platform hoist which is relatively inexpensive and easy to manufacture, yet which is rugged 4and capable of delivering long, trouble-free service.
It is another object of the invention to'provide a platform hoist which is simple to operate and maintain.
It is still another object of the invention to provide a platform hoist which is light-weight and highly mobile, and can, ltherefore, be easily moved from one location to another.
It is a still further object of the invention to provide a platform hoist Which raises and lowers with great rapidity and which, therefore, enables a construction crew quickly to lift a piece of plaster board, for example, to the height required.
It is another object of the invention to provide a material hoist which not only enables a carpenter to raise a piece of building material to the ceiling but which also holds the board in position against the ceiling joists while nailing of the board is eected.
lt is a still further object of the invention to provide a platform hoist which is self-stabilizing and which, therefore, permits of considerable unevenness in loading and yet which maintains the platform at all times in a proper horizontal attitude.
It is yet a further object of theY invention to provide a platform hoist which, owing to a weight-counter-balancing feature, enables the user to raise the hoist and equipment placed thereon relatively easily and which, also, during the lowering of the hoist exerts but little strain or effort on the operating personnel.
It is a still further object of the invention to provide a platform hoist having a brake which permits the platform to be securely locked in any desired elevated position.
It is yet another object of the invention to provide a generally improved platform hoist.
Other objects, together with the foregoing, are attained in the embodiment described below and shown in the accompanying drawings in which:
Figure 1 is a side elevation of the platform hoist in a position of medium elevated height.
Figure 2 is a section taken along the folded planes indicated by the line 2-2 of Figure l.
Figure 3 is a section taken along the offset planes in* dicated by the line 3-3 of Figure 2.
Figure 4 is a plan View showing the gear box and the brake and crank mechanism, the view being generally indicated by the line 4 4 of Figure 1, with a portion of the figure being broken away to reduce the extent thereof.
Figure 5 is a vertical section of the brake and crank mechanism to an enlarged scale, the plane of section being indicated by the line 5--5 of Figure 4.
nited States Patent O 2,901,896v Patented Sept. 15, 1959 ICC Figure 6 is a vertical sectional vieW of the brake and crank mechanism, the plane of section being indicated by the line 6--6 of Figure 5.
Figure 7 is a side elevational View of a modified form of the platform stabilizing mechanism, a portion of the gure being broken away to reduce the extent thereof.
Figure 8 is a side elevation of the platform hoist shown in semi-diagrammatic form and showing the platform hoist in lowermost position.
Figure 9 is a view similar to that of Figure 8 but showing the hoist in a somewhat elevated position.
Figure 10 is a view similar to that of Figure 9 but showing the platform hoist in a still more elevated position.
Figure 11 is a view similar to that of Figure l0 but showing the platform hoist in uppermost or highest position.
The platform hoist of the invention is susceptible of numerous physical embodiments depending upon the particular environmental situation to be met, but -several of the herein disclosed hoists have been made and used, and have performed in an eminently satisfactory fashion.
Supported on ground-engaging wheels 21 is a frame 22 including a pair of bottom rails 23, top rails 24 and vertical stanchions 26 and 27, braced by angle supports 28 and 29.
Spanning the stanchions 26 and 27 of the framework are horizontal cross members 31 and 33 serving to support a brake and hand crank mechanism 32 including a gear box 34.
The mechanism 32 includes `an angle iron 36 secured to the member 31. A bearing sleeve 37 mounted on the angle iron 36 confines and supports a rotatable transverse shaft 38. Mounted rigidly on and firmly fastened to the angle iron 36 is a brake drum 41 having a flange 42. A boss 43 has `a bore 44 serving as an additional journal. To the outermost end 46 of the shaft 38 is firmly secured a radial crank arm 47. The free end of the crank arm 47 carries brackets 48 having apertures 49 receiving a pivot pin 51. Mounted on the pin 51 is a handle 52 having a hand-hold 53, and having a cheek 54 provided With an aperture 45 receiving the pin 51. The handle 52 pivots about the pin 51 as a fulorum.
When cranking is to be performed, the operator first grasps the hand-hold portion 53 and pulls it in the direction of the arrow 50 into the outlined position 56, in which the handle projects through and is guided by a slot 55 in the crank arm 47. The crank arm 47 is rotated as the crank handle 56 is turned and so rotates the shaft 38 and the various gears within the gear box 34.
When the crank handle 52 is rotated to the cranking position 56, the uppermost end 61 of the crank handle is rotated to an outlined position 62 to release the brake mechanism. Inward swinging or rotation of the uppermost end 61 of the crank handle about the fulcrum, pin 51 is accompanied by a corresponding swinging or rotation of a pivot pin 63. This passes through an aperture 64 in the crank handle iand through apertures 66 in straddling straps 67, bent to confine a block 68. A pin 69 goes through the block and through apertures 7) in the straps. The block 68 is fastened to a stem 71 including a rod 72 slideable in an aperture 73 in a bracket 74 on the crank 47. The rod 72 extends through an opening 76 in a yoke 77 and is secured therein by a nut 78 inteiposed between the yoke 77 and the fixed bracket. A compression spring 79 bearing against the bracket '74 urges the rod 72 and yoke 77 downwardly. Mounted on the legs 80 of the yoke 77 by rivets 81 is a brake band 82 encircling the brake drum 41. Rotation of the crank handle into the cranking position 56 releases the brake.
Braking is effected by pushing the crank handle to the full line position in Figure 5, thus drawing the brake band 82 to engage the fixed brake drum,
Since the spring 79 is displaced from the center of the fulcrum pin 51, the spring tends to hold the crank handle and the brake in a locked position.
When the brake band 82 is firmly against the brake drum, it prevents the rotation of the crank arm 47 and the associated parts. When the crank handle 52 is swung outwardly far enough, the spring 79 not only releases the brake but `swings the crank handle the rest of theV way into cranking position.
The gear box 34 includes side Walls 101 and 102 and end Walls 103. A pair of bearings 106 support the end of the shaft 38. Mounted on the shaft 38 is a gear 107 meshing with a spur gear 108 which itself meshes with a spur gear 109. The spur gears 108 and 109 are mounted on shafts 111 and 112 journalled in bearings 113 and 114. Torque from the shaft 38 is transmitted through the gear 107 to the spur gear 108 and thence totheV spur gear 109. The spur gears 108 and 109 rotate equal amounts in opposite directions.
Rotation of the spur gears 108 and 109 is transmitted through the shafts 111 and 112 to sprocket chains 116 and 117 reeved about sprocket gears 118 and 119 fastened on the shafts 111 and 112.
The sprocket chains 116 and 17 and the attendant hoist structure are substantially symmetrical about a plane 20. The description describes the construction and operation of the mechanism on both sides of the plane 120.
The sprocket chain 117 is reeved about a sprocket gear 121 securely mounted on one end of a transverse shaft 122 journalled within a sleeve 123 fast on the supporting stanchions '26. On the shaft 122 are base blocks 124 and 126, the latter being fast on the sprocket gear 125. Mounted on each of the base blocks 124 and 126 is a primary arm 127 including strut members 128 and 129 and a cross brace 131. Mounted on the outermostends of the arms 127 is a pair of spaced apart sleeves 132 and 133 supported by diagonal struts 134 and 135.
Journalled within the sleeves 132 and 133 is a transverse shaft 136 having mounted thereon a pair of flanges 138 and 139. Mounted on the flanges 138 and 139 are secondary arms 142 and 143 including struts 144 and 145 terminating in sleeves 146 and 147. A pair of pins 148 and 149 journalled in the sleeves 146 and 147 car1y a third pair of arms 150 and 151 comprising a pair of diverging struts 152 and 153. The struts 152 and 153 support a platform framework 154 on which a piece of material 155, such as plaster board or plywood, is disposed.
The primary arms 127, the secondary arms 142 and the supports 150 are moved with respect to each other and to the framework.
Rotation of the left sprocket gear 121 causes a correspending rotation, for example, in a clockwise direction, of the left primary arms 127. As the arms 127 are rotated to the position designated 161, the sleeves 132 and 133 and the shaft 136 are also moved upwardly. The shaft 136 is revolved about the center line 162 of the shaft 122. A similar revolution is imparted to a small sprocket gear 163 secured to the shaft and disposed between the sleeves 132 and 133. Reeved about the small sprocket gear 163 is a sprocket chain 164 also reeved over a fixed large gear 166 mounted on the sleeve 123. The chain 164 has ends fastened to the wheel 166 at 167 and 168.
As the left arms 127 are swung upwardly, as shown by the arrow 170, to the position 161, the upper chain run is progressively reeved off the wheel 166 and translates toward the left in Figure 3 and the lower run is reeved `around the wheel 166. Rotational movement is thus imparted to the sprocket gear 163 in the counterclockwise direction of the arrow 169. When the arms 127 are swung downwardly, as shown by the arrow 171, the sprocket wheel 163 is rotated clockwise, as designated by the arrow 172.
The upward clockwise swinging motion of the sprocket wheel 163 and the shaft 136 is accompanied by rotation in a counterclockwise direction of the gear 163 and the shaft 136. This swings the secondary arms 142 in a counterclockwise direction about the center line 176.
Preferably, the pivot pins 148 and 149 travel in a vertical line inclusive of the center line 162 of the shaft 122. The distances between the axes 162 and 176 and between the axis 176 and the axis 175 are made to coincide, and the root diameter of the gear 163 is made onehalf the root diameter of the fixed wheel 166. The platform supports are thus caused to move in a predetermined vertical plane and to retain a fixed horizontal attitude at all times.
While the parallelism of the pivot pins 148 and 149 and the pairs of platform supports at each end of the frame is maintained satisfactorily, an additional assurance of parallelism is provided by a pair of members 181 connecting the corresponding pivot pins 148 and 149 at the bottom of the platform supports.
Any tendency of the platform and the attached vertical platform supports to tilt owing to an unbalance of weight thereon is countered by a stabilizing mechanism 201. included on each platform support is a strut 202 pivoted by a pin 200 to a bracket 203 on the strut 144. At the top of the strut 202 on a pin 199 is a rocking member 204 including a rocker arm 208. A yoke 205 on the arm 208 has arcuate portions 206 and a cross brace 207. At the intersection of the rocker arm 208 and the cross brace 207, the rocking member 204 is pivotally mounted on a pin 210 on a horizontal brace 211. Extending from the upper yoke arm of the left-hand rocking member 208 to the lower yoke arm of the righthand rocking member 208 is a first lever 216 connected to the yokes by a pair of sprocket chains 217. Connecting the opposite sides of the yoke arms is a cross lever 218-. This is done by a pair of sprocket chains 219.
The interaction of the foregoing components serves to stabilize the platform.
Figure 7 illustrates a modified form of the stabilizing mechanism comprising a left-hand rocking member 231 and a right-hand rocking member 232, each including a strut 233 mounted on a corresponding pivot pin 199. An upper yoke arm 234 and a lower yoke arm 235 are mounted on the strut 233 and terminate in a quadrant 236 having teeth 237 and bracing arms 238. The rocking member is pivoted about a pin 239 mounted on a cross brace 241 extending between the adjacent struts of the Vertical platform supports. The cross brace 241 serves to transmit any unbalancing forces from one side of the platform to the other side.
The task of the user in cranking the Idevice to its upper most or lowermost position can be greatly simplified by the provision of a weight counter-balancing mechanism. Rotatably mounted on the bearing Sleeve 123 is a wheel 252 having a peripheral slot 253 and a flange 251i. Mounted firmly on the sleeve bearing 123 is a collar 256 having a flange 257 adjacent the Wheel flange 254. Over the upper edge 253 of the flange 258 is bent one end of a helical coiled spring 259, the other end 261 being in a slot 262 in the wheel 252. The wheel 251 rotates in such direction as to store energy in the spring during the lowering of the platform hoist and to release energy during the lifting of the hoist. This also serves to cushion the hoist when it is being lowered.
Secured in a peripheral slot 253 in the wheel 252 by a fastening 266 is a flexible cable 268 reeved about the Wheel 252 and taking off from the top side of the large wheel 252, leading to the lower side of a small wheel 271. This is secured to the transverse shaft 136, the cable being within a slot 272 in the wheel 271 and being fastened by a fastening 273.
As the arm 127 rotates in a counterclockwise direction 171, the gear 163, the shaft 136 and the rwheel 271 are rotated in a clockwise direction, as shown by the arrow 172. With the clockwise rotation of the wheel 271, the flexible cable 268 is pulled and the rotatable wheel 252 is rotated in a counterclockwise direction. The spring 259, previously undistorted, is caused to contract and store energy.
When the hoist is raised, the primary arm 127 is rotated in a clockwise direction 170 and the energy of the spring 259 causes the Wheel 252 to rotate in a clockwise direction. Clockwise rotation of the Wheel 252 causes the flexible cable 268 to be pulled toward the right. The force exerted by the cable to augment the force of the sprocket chain 164 is thus benecial. The energy stored in the spring during the lowering of the hoist is released during raising thereof.
The hoist in its lowermost position provides a horizontal platform at a height convenient for the average workman to load material onto the platform. The height of the platform at its uppermost position is of the order of three times the height of the platform in its lowermost position.
The primary and secondary arms do not extend outwardly beyond the ends of the platform itself and can be reversed so that movement of the arms takes place between the vertical planes 180.
Figure 11 shows the platform hoist at its uppermost location in a neutral or dead center position. As the weight of the structure and the load is imposed vertically downwardly upon the sup-porting members of the framework, no rotational component is impressed on the hoisting structure.
The spring force counterbalances the weight of the struct-ure and load which otherwise would act against the brake mechanism. Thus, even in the intermediate positions, the brake mechanism is assisted.
It can therefore be seen that a platform hoist is provided which attains in an eminently satisfactory fashion the objects of the invention heretofore recited.
What is claimed is:
1. A platform hoist comprising a frame, a iii-st shaft journalled in said fname, a primary arm mounted on said first shaft, a second shaft journalled on the free end of said primary arm, a secondary arm mounted on said second shaft, ya drum fixed on said frame coaXially with said iirst shaft, a sprocket coaxially mounted on and rotatable in unison with said second shaft and in substantially coplanar relation with said drum, 'and a chain reeved about said sprocket and secured at both ends to said drum whereby rotation of said primary am and said rst shaft in one direction effects rotation in the opposite direction of said sprocket, said second shaft and said secondary arm.
2. A platform hoist comprising a frame, a first shaft journalled in said frame, `a primary arm projecting radial- 1y from Said rst shaft, a second shaft journalled on the free end of said primary arm, a secondary arm projecting radially from said second shaft, a drum fixed on said frame concentrically with said -iirst shaft, a sprocket securely mounted on said second shaft and concentrically therewith, a chain reeved about said sprocket and about said drum, means for rotating said rst shaft, and spring means connecting said frame and said second shaft for releasing energy `as said second shaft turns in one direction of rotation and for storing energy -as said second shaft lriurns in the other direction of rotation said spring means including a exible cable reeved about said second shaft and tensioned thereby as said second shaft turns in said other direction of rotation.
References Cited in the tile of this patent UNITED STATES PATENTS 226,101 Pfautz Mar. 30, 1880 583,034 Davis May 25, 1897 732,418 King June 30, 1903 740,398 Cheves Oct. 6, 1903 2,471,901 Ross May 31, 1949 FOREIGN PATENTS 260,087 Italy Sept. 5, 1928 424,764 Great Britain Feb. 18, 1935