Chain Tightener for Drive Chain

Mobile shelving apparatus employs a plurality of mobile units which move in rectilinear fashion and are guided for movement by tracks supported on the floor. Some apparatus of this character employs reversible drive motors for driving each unit. U.S. Pat. No. 3,640,595 is illustrative of a system of that type. Other systems use a positive manual drive with a manual wheel or crank operable by the user.

The invention provides a chain tensioning device for a manually operable storage apparatus so that slack can easily be taken out of the chain and provide a positive feel to the handle. The device is adapted to be retro-fitted to existing installations and includes a ball bearing assembly with an outer race in a press fit in a mounting block, with the inner race sized to be journalled on the drive shaft of the unit. Bolts threadably received in the mounting block are engaged with a base plate, whereupon tightening of the bolts draws the mounting block against the bolt support to slightly deflect the drive shaft and tighten the chain.

Further objects, advantages and features of the invention will be apparent from the disclosure.

FIG. 1 is a fragmentary perspective view of mobile storage apparatus provided with the chain tensioning device of the invention.

FIG. 2 is an enlarged end view of the apparatus shown in FIG. 1.

FIG. 3 is an enlarged side elvational view of the apparatus shown in FIGS. 1 and 2.

FIG. 4 is an enlarged view of the bearing block.

Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention which may be embodied in other specific structure. The scope of the invention is defined in the claims appended hereto.

In the drawings, FIG. 1 shows a mobile storage unit 10 having an end face 12 and sides 14 and 16 which typically are provided with shelving for storage of materials. As illustrated in FIG. 3, the storage unit is guided for movement by a guide track 17 anchored to the building floor 18. A positive driving connection to the building floor can be employed using a sprocket 20 connected on drive shaft 22 which engages a sprocket chain 24 which is secured to the floor 18 in a plane parallel to the floor. The shaft 22 and sprocket 20 are driven by a manually operable crank handle, spoke or wheel 30 supported on a shaft 32 which is rotatably supported by a bearing 34 on a panel or housing channel 36. A first sprocket 38 is fixed to shaft 32 and connected by a chain 40 to a second sprocket 42 to rotate the shaft 22 and sprocket 20. Fixed shaft supports are provided to rotatably support the shaft 22. The fixed shaft supports can be pillow blocks 21 mounted on the storage unit panel as shown in our U.S. Pat. No. 3,640,595, FIG. 11 and described at column 3, lines 19-24 of the latter patent which is incorporated herein by reference.

In accordance with the invention, a chain tensioning device 50 is disclosed which includes a bearing block 52 which has an aperture 54 which receives the outer race 56 of a roller bearing 58. The outer race can be in a press fit in the aperture 54. The inner race 60 is journalled on the shaft 22. The bearing block 52 is connected to a support block 64 by bolts 66 which extend through apertures 68 in the block 64 and are threadably received in threaded apertures 70 in the block. Tightening the bolts 66 causes tension against the end of the shaft 22 to deflect the shaft, but the ball bearings permit free rotation of shaft 22. Tightening the bolts 66 will draw up the chain to take the slack out of the chain and provide the desired tension and feel to the wheel 30.

The chain tensioning device of the invention is designed to be retro-fitted by field installation to existing units. The bearing block is readily slipped over the free end of the shaft 22 and the block positioned at the end of the housing channel 36.