Bucket elevator

A boot-driven bucket elevator apparatus for bulk material handling is provided with a boot pulley drive and take-up which effects rotation of the apparatus co-operating bucket endless belt, which is platform lever-mounted, and which automatically effects proper tensioning and centering of the apparatus endless belt by the gravitational weight of the drive and take-up.

CROSS-REFERENCES
 None.
 FIELD OF THE INVENTION
 This invention pertains generally to bulk material handling equipment, and
 particularly concerns boot-driven bucket elevator apparatus as
 distinguished from head-driven bucket elevator apparatus.
 BACKGROUND OF THE INVENTION
 Bucket elevator apparatus utilized for lifting granular bulk materials such
 as food grains for storage or for other processing may be generally
 classified as being either head-driven or boot-driven in their principal
 mode of operation. Each elevator category typically includes a
 vertically-oriented endless belt which co-operates both with an upper
 pulley and with a lower pulley, and to which are attached multiple,
 spaced-apart, material-carrying bucket elements. The elevator primary
 drive is operatively connected to the upper pulley in the case of
 head-driven bucket elevators and to the lower pulley in the case of
 boot-driven bucket elevators. A suitable housing with supply and discharge
 openings encloses the bucket elevator pulleys, endless belt, and attached
 material-carrying buckets.
 Heretofore, the type of bucket elevator preferred in the United States has
 been the head-driven type with the apparatus primary drive being
 operatively connected to the elevator upper pulley. However, in instances
 when large vertical-movement distances are involved and the apparatus
 primary drive is located at a substantial height above ground,
 accessibility to the drive mechanism for maintenance servicing or
 replacement is significantly reduced and is to be avoided.
 With respect to boot-driven bucket elevator apparatus, substantial belt
 slippage, belt tensioning control, and belt-to-pulley alignment problems
 have heretofore been encountered, especially when high rates of material
 movement (e.g., 32,000 bushels of grain per hour) or large vertical
 material-movement distances (e.g., 300 vertical feet) are involved. One
 known, albeit unnecessarily complex, apparatus resolution to such bucket
 elevator needs is the boot pulley hydraulic drive with included
 creep-drive and belt take-up features that is disclosed and claimed in
 U.S. Pat. No. 4,799,584 issued in the name of Hartsuiker, et al.
 Accordingly, a principal objective of the present invention is to provide a
 bucket elevator having a boot pulley with a boot pulley primary drive with
 a take-up that obtains simplified belt tensioning control and
 consequential reductions in belt slippage and belt slippage heat
 generation, belt wear, belt-to-pulley misalignment, cost of elevator
 manufacture, and cost of elevator drive maintenance servicing and
 replacement.
 Other objects and advantages of the present invention will become apparent
 from a consideration of the descriptions, drawings, and claims which
 follow.
 SUMMARY OF THE INVENTION
 The bucket elevator apparatus of the present invention is basically
 comprised of an upper or head pulley element, a lower or boot pulley
 element, an endless belt element having attached spaced-apart
 material-carrying bucket elements and co-operating with both pulley
 elements, a housing enclosing the foregoing elements, and a primary drive
 operatively connected to the lower or boot pulley element. The primary
 drive includes an electric motor, a coupling mechanically joining the
 output shaft of the electric motor to the shaft of the apparatus boot
 pulley element, floating bearing elements supporting the shaft of the boot
 pulley element, a boot fulcrum element, and a platform-like boot lever
 element co-operating with the boot fulcrum element, the electric motor
 element, and the floating bearing elements in a manner whereby the weight
 of the electric motor element continuously applies gravitational
 tensioning forces to the drive floating bearing elements, the boot pulley
 element, and the apparatus endless belt element.

DETAILED DESCRIPTION
 FIG. 1 schematically illustrates a preferred embodiment of the bucket
 elevator apparatus of the present invention which is referenced as 10 in
 the drawings, and which is essentially comprised of: upper or head pulley
 12; lower or boot pulley 14; endless belt 16 having material-carrying
 bucket element 18 attached thereto and co-operating with pulleys 12 and
 14; and housing 20 that encloses elements 12 through 18 and that is
 provided with material supply inlet 22 and material discharge outlet 24.
 Referring to FIGS. 2 and 3, boot pulley element 14 is mounted on a shaft
 26 that is guided by conventional roller bearings 28 in pillow blocks 30
 mounted to slide 29. Shaft 26 is guided within slot 31 formed in housing
 20. Pillow blocks 30 are free to float relative to housing 20 but only in
 upward or downward vertical directions within slot 31 because of the
 restriction effected by their co-operation with fixed guide elements 32
 mounted on housing 20. Apparatus 10 also includes the primary drive 40
 that rotatably powers boot pulley element 14 to cause movement of pulleys
 14 and 12 and endless belt 16 in the directions shown by the directional
 arrows of FIG. 1.
 As more clearly shown in FIG. 2, primary drive and belt take-up 40 is
 basically comprised of electric motor 42 rigidly mounted on platform lever
 44, and having its motor output shaft connected to boot pulley shaft 26
 successively through gear reduction unit 46, gear reducer drive sprocket
 or drive sheave 48, endless chain or V-belt 50, and drive sprocket or
 drive sheave 52 which is keyed or otherwise rotationally secured to boot
 pulley shaft 26. Platform element 44 carries an attached pair of rigid
 lever arm elements 54 that carry bearing element pillow blocks 56 on their
 underside. Pillow blocks 56 support boot pulley shaft 26. Lever arm
 elements 54 contact and co-operate with cylindrical fulcrums 58. Each end
 of fulcrum 58 is supported by one end of a vertical channel member 60
 which is affixed to and projects upwardly from elevator base 62.
 Thus, principally due to the weight of electric motor 42 (which in practice
 often is a 150 or larger horsepower electric motor) and platform lever 44
 and its attached arms 54, primary drive and take-up 40 applies
 longitudinal belt-tensioning forces to boot pulley 14 as well as
 rotational forces. When platform 44 and attached lever arms 54 are
 automatically pivoted about fulcrums 58 to accommodate changed tensioning
 requirements for endless belt 16, the attached arms 54 will slide
 longitudinally relative to fulcrums 58 because of the consequently-changed
 position of boot pulley shaft 26. Arms 54 must move longitudinally
 relative to fulcrums 58 because boot pulley shaft 26 only can move
 vertically in fixed guide elements 32.
 Various changes may be made to the configurations, proportionate sizes,
 placements, and materials of construction of the invention elements
 described herein without departing from the scope, meaning, or intent of
 the claims which follow.