US2776059A

US2776059A - Skip hoist

Info

Publication number: US2776059A
Application number: US357861A
Authority: US
Inventors: Huber Albert Lloyd
Original assignee: Link Belt Co
Current assignee: Link Belt Co
Priority date: 1953-05-27
Filing date: 1953-05-27
Publication date: 1957-01-01
Anticipated expiration: 1974-01-01

Description

A. L. HUBER Jan. 1, 1957 SKIP HOIST ll Sheets-Sheet 1 Filed May 27, 1953 Jan. 1, 1957 Fild May 27, 1953 Jan. 1, 1957 A. L. HUBER 2,776,059

SKIP HQIST Filed May 27, 1955 11 Sheets-Sheet 3 11 Sheets-Sheet 4 SKIP HOIST A. L. HUBER Jan. 1, 1957 Filed May 27, 1955 A. L. HUBER Jan. 1, 1957 SKIP HOIST 11 Sheets-Sheet 5 Filed May 27, 1953 A. L. HUBER Jan. 1, 1957 SKIP HOIST File d May 27, 1953 ll Sheets-Sheet 6 A. L. HUBER Jan. 1, 1957 SKIP HOIST ,ll Sheets-Sheet 7 Filed May 27, 1953 Jan. 1, 1957 HUBER 2,776,059

SKIP HOIST Filed May 27, 1953 ll Sheets-Sheet 8 A. L. HUBER Jan. 1, 1957 SKIP HOIST ll Sheets-Sheet 10 Filed May 27, 1953 kw m A. L. HUBER SKIP HOIST ll Sheets-Sheet 11 Filed May 27, 1953 5 w m 5. 4 my M i/ .W /0 E i W a 1 L w T; p III d B 1 mm Ac m {If 2% M United States Patent SKIP HOIST Albert Lloyd Huber, Toronto, Ontario, Canada, assignor to Link-Belt Company, a corporation of Illinois Application May 27, 1953, Serial No. 357,861

17 Claims. (Cl. 214-16) This invention relates to new and useful improvements in skip hoists which operate automatically to raise the material being handled to the desired elevation and then effect its discharge at any preselected location along a horizontal path of travel so that the material may be delivered, at the will of the operator, to different, horizontally arranged storage bins or silos.

It is standard practice at this time to employ in combination a skip hoist and an elevated, horizontally arranged belt conveyor, equipped with a traveling tripper, for transferring fiowable solids from a railway track hopper, or the like, to the top receiving openings of a plurality of above ground storage bins or silos. The skip hoists function to elevate the materials to approximately the levels of the tops of the bins or silos and then dis-.

charge the materials into transfer hoppers. The belt conveyors receive the materials from the transfer hoppers and carry the same horizontally to the locations of the openings in the tops of the storage bins or silos. The positions of the traveling trippers for the belt conveyors, of course, determine the locations at which the materials are finally discharged into the bins or silos.

This arrangement of: equipment has been unsatisfactory tor the handling of certain materials because of the undesirable degradation that has occurred as a result of transferring the materials from the skip hoist to the horizontal conveyor.

It is the primary object of this invention to provide a skip hoist which will raise the material being handled to the desired elevation, convey it horizontally to any preselected one of a plurality of possible delivery points and then automatically discharge the material.

A further important object of the invention is to provide a skip hoist of the above mentioned type in which the material conveying bucket is automatically dumped at any desired location along its horizontal path of travel by a-previously positioned traveling discharge mechamsm.

Still another object'of the invention is to provide a skip hoist having a material conveying bucket which iscaused to travel in opposite direction along a combined vertical and horizontal path; and in which the direction, speed, and time of travel, and the point of discharge of the bucket are all automatically controlled to effect repeated bucket filling and dumping cycles of operation regardless of the changes that will occur in the distance the bucket travels during its cycles as a result of changes that are made, from time to time, in the location along the horizontal portion of its path of travel at which the bucket is actuated to effect dumping of the material. 7

Other objects and advantages of the invention will be apparent during the course of the following description.

In the accompanying drawings forming a part of this specification and in which like reference characters "are:

employed to designate like parts throughout the same,

Figure l is a side elevational view of a skip hoist in-' stallation embodying the invention,

Figure 2 is a plan view of the skip hoist with its ma 2 terial handling bucket at a discharge position at the outer end portion of the installation,

Figure 3 is a top plan View of the intermediate portion of the horizontal guideway for the skip bucket,

' Figure 4 is a side elevational view of the portion of the installation illustrated in Fig. 2,

in its loading position at the lower end of the skip hoist installation,

Figure 10 is a vertical sectional view taken on line 10-'-10 of Fig. 9,

Figure 11 is a diagrammatic view showing the cable systems by means of which the skip bucket and its discharge mechanism are propelled and the arrangement of the control devices for the skip bucket,

Figure 12 is a wiring diagram of the electrical circuits for the control elements and the skip hoist motor,

Figure 13 is a top plan view of the drive unit for the skip bucket, and

Figure 14 is a vertical sectional view taken on line 14-14 of Fig. 3.

In the drawings, wherein for the purpose of illustration is shown the preferred embodiment of this invention, and first particularly referring to Figs. 1 and 9, there is shown a track hopper 29 for receiving material from railway car 21, or the like. The hopper 20 is suitably supported in a pit 22 of sutiicient depth to accommodate the discharge spout 23 of the hopper which is provided with a fullbucket-control type automatic loader 24. The loader 24 will be more fully described at a later point.

Rising vertically from one side of the bottom of the pit 22 is a supporting trestle 25 that is constructed in a conventional manner. A protective shelter 26 may be suitably positioned at the top of the trestle 25 and supported on the trestle and on laterally spaced vertical posts 27. Spaced horizontally from the vertical trestle 25 are two or more storage bins or silos 28, which are elevated to assist in unloading the material that is stored therein, and with the tops of the bins being arranged in substantially horizontal alinement.

A guideway 29 extends horizontally across the tops of the bins 28 and to the protective shelter 26 where it curves downwardly along the trestle 25 to the pit 22. The portion'of the guideway 29 within the pit 22 is slightly in clined so that the-guideway passes adjacent the loader 24. A second guideway 31 is mounted below the horizontally extending portion of the guideway 29.

Mounted for movement along the guideway 29 is a wheeled carriage 32 having a skip bucket 33 pivotally The reel 36 is rotated by a motor 37 through a speed reducer 38 and a pair of

spur gears

39 and 41.

Mounted for movement along the guideway 31 is a traveling bucket dumping mechanism 42 which, as will I be later described, may be stopped at any selected point along the horizontally extending portion of the guideway 31 to efi'ect tilting of the bucket 33 relative to its carriage 32 to discharge the material from the bucket into one of the bins 28. Movement of the dumper 42 is etfected by operation of the winch 43 through

cables

44 and 45.

Referring now to Figs. 2 to 8, inclusive, and 14 for a detail description of the structure so far described, the guideway 29 is formed by a pair of laterally spaced supporting rails 46 and a pair of keeper rails 47 which are arranged in vertically spaced relationship with the supporting surfaces of the rails 46. The rails 46 are mounted on I-beams 48 positioned at each side of the guideway 29 and the I-beams are supported at spaced points along their lengths by posts 49 that are mounted on girders 51 extending transversely across the bins 28. As is best illustrated in Fig. 7, the keeper rails 47 are connected directly to the upper end portions of the posts 49. On one side of the guideway 29, pulleys 52 are mounted outwardly of the posts 49 and, on the other side of the guideway 29, skid plates 53 are mounted adjacent the base of each post 49. The function of the pulleys 52 and skid plates 53 will be later described.

The guideway 31 is formed by -a pair of rails 54 which are positioned below and in spaced relationship with the inner edges of the lower flanges of the I-beams 48 and are supported by longitudinally extending I-beams 55 on opposite sides of the guideway 29, see Fig. 7. The lower flanges of the I-beams 48 function as keeper rails for the guideway 31. The I-beams 55 are supported at spaced points along their lengths by the girders 51.

As best illustrated in Figs. 2, 4, and 6 the carriage 32 is formed with a body 56 and a bail 57. The sides of the body 56 are formed by longitudinally extending bars 58 which are connected at their trailing end portions by a pair of channel beams 59 arranged in spaced back-to-back relationship. A pair of stub axles 60 are mounted between the end portions of channel beams 59 on opposite sides of the carriage body 56 with the outer ends of the axles projecting laterally from the carriage body and having wheels 61 mounted thereon, see Figs. 2 and 5. As illustrated in Fig. 6, the portions of the stub axles 60 which lie between the channel beams 59 are square in cross-section and the rounded portions of the axles extend intothe spaces between the

rails

46 and 47 of the guide way 29.

Extending through transversely alined openings in the leading end portions of the side bars 58 for angular movement relative to the side bars is an axle 62, the middle portion of which is square in cross-section. Between each side bar 58 and the square middle portion of the axle 62 there is pivotally mounted on the axle an arm 63 for the bail 57, see Fig. 5. The rounded ends of the axle 62 extend outwardly from the side bars 58 of the carriage body 56-into the space between the

rails

46 and 47 and a wheel 64 is mounted on each of these projecting ends.

The side arms 63 of the bail 57 have their free end portions rigidly connected by a pair of channel beams 65 arranged in spaced back-to-back relationship. Stub axles 66 are mounted between the end portions of the beams 65 on both sides of the bail 57 and project laterally into the spaces between the

rails

46 and 47. That portion of each stub axle 66 which is positioned between the channel beams 65 is square in cross-section for rigid connection to the beams. The end portions of the stub axles 66 between the

rails

46 and 47 are rounded and have mounted thereon wheels 67. It will be readily apparent that the

wheels

61 and 64 of the carriage body 56 and the wheels 67 of the bail 57 will restrict movement of the carriage 32 to a path along the guideway 29 but will permit pivotal movement of the bail relative to the body of the carriage.

A gate 68 extends transversely between the side arms 63 at the outer end portion of the bail 57 and projects arcuately upwardly from the side arms. The end edges of the gate 68 and the side arms 63 are connected by side plates 69. Angle irons 71 are mounted along the edges of the side plates 69. It will be noted that one of the angle irons 71 of each of the plates 69 is arranged in radial relationship with the axle 62 at the leading end portion of the carriage body 56. As best illustrated in Fig. 6, the skip bucket 33 is positioned on the carriage body 56 and the bottom wall 72 of the bucket is rigidly connected to the square middle portion of the axle 62 by a pair of angle irons 73. The length of the skip bucket 33 is such that its end wall 74 is alined with the innermost channel beam 59 at the trailing end of the carriage and the portion of the mouth of the bucket adjacent the bottom wall 72 lies in closely spaced relationship with the gate 68 on the bail 57. The bucket 33 is so balanced that it will remain in flatwise relationship with the carriage 32 in both its vertical and horizontal paths of travel. The side walls 75 of the bucket 33 are formed with arcuate end edges adjacent the gate 68 to permit pivotal movement of the bucket and its axle 62. Mounted on each side wall 75 is an angle iron 76 which is radially arranged relative to the axle 62 for engagement with the radially arranged angle iron 71 on the bail 57 to limit the downward pivotal movement of the bucket 33.

Extending outwardly from each side wall 75 of the bucket, at the end wall 74, is an axle 77 having a roller 78 mounted thereon for a purpose that will be later described. The top wall 79 of the bucket 33 has mounted thereon a pair of transversely spaced loader actuating arms 81 which are provided with rollers 82 at their outer end portions. Positioned between the arms 81, on the top wall 79 are a pair of wear straps 83 which are bent around the edge of the top wall 79 at the mouth of the bucket 33.

A follower bracket 84 is mounted on each side of the bottom wall 72 and extends downwardly therefrom between the

axles

60 and 62 of the carriage body 56, see Fig. 6. Each of the brackets 84 is formed of a pair of laterally spaced plates 85 with stiffening webs 86 connected therebetween and with a follower roll 87 rotatably mounted between the lowermost portions of the plates.

Referring now to Fig. 11 for a detail description of the cable system for propelling the carriage 32 and bucket 33, it will be seen that the cable 34, which is employed for advancing the carriage and bucket from the loading position to the discharge point, rises substantially vertically from the reel 36 to a guide pulley 88 mounted at the outer end of the guideway 29. The cable 34 wraps partially around the pulley 88 and extends longitudinally along the guideway 29 for connection to the carriage bail 57. As is best illustrated in Figs. 1 and 2, the pulley 88 is mounted on a frame 89 projecting from the side of one of the bins 28 and supported by angularly arranged braces 91. The cable 34 is connected to the bail 57 by a pin 92 mounted on the bail, as is best illustrated in Fig. 8.

The return cable 35 rises substantially vertically from the. reel 36 and is partially wrapped around a guide pulley 93, located at the outer end and to one side ot the guideway 29, and then extends longitudinally along the guideway where it is supported by rollers 52. The pulley 93 is mounted adjacent the base of one of the end posts 49 of theguideway 29, as is best illustrated in Figs. 2 and 4. At the inner end portion of the honzontally extending section of the guideway 29, two longitudinally spaced counterweight supporting pulleys 94 are mounted substantially in alinement with the rollers 52 so that a take-up loop may be formed in the cable 35 between the supporting pulleys. Supported by the takeup loop is a counterweight pulley 95 from which is suspended the counterweight 96. As is best illustratcd in.

Fig. 3, the supporting pulleys 94 are mounted on a takeup frame 97 .at one side of. the guideway 29. The takeup frame 97 extends downwardly from the guideway 29 to provide a guide for the vertical movements of the counterweight 96 as the lengths of the

cables

34 and 35 vary. 1

From the counterweight supporting pulleys 94, the cable 35 passes over a, pair of guide pulleys 98 and extends downwardly along one side of the guideway 29 at the trestle 25. A guide pulley 99 is mounted at approximately the level of the top of the pit 22 for supporting the cable 35 as it moves between the vertically extending and inclined portions of the guideway 29. At the lower end of the guideway 29 the cable 35 is trained around a pair of pulleys 101 from which it extends upwardly for connection to the trailing end portion of the carriage body 56 by means of the eyebolt 104.

It will be appreciated that when the carriage body is in the position for dumping the skip bucket 33, as seen in Fig. 11, the cable 35 must extend back up the trestle 25 and along the horizontal portion of the guideway 29 to this location of the carriage body. A guard roller 102 and three guide pulleys 103 are provided for supporting the cable 35 under these conditions. However, when the carriage body 56 is in the position for filling the bucket 33, as seen in Figs. 1, 9 and 10, the cable 34 will extend along the horizontal portion of the guideway 29 and down the trestle 25. The three guide pulleys 103 and the guard roller 102 then will support the cable 34 instead of the cable 35.

As illustrated in Fig. 1, the guide pulleys 103 are located a sufficient distance inwardly of the guideway 29 to permit free movement of the carriage 32 over the pulleys in passing between the vertically and horizontally extending portions of the guideway. The guard roller 102 is spaced a suflicient distance outwardly of the guideway 29 to permit movement of the bucket 33 therebetween the purpose of the roller being to prevent engagement of either of the

cables

34 or 35 with the hopper 20.

Referring now to Fig. 13, it will be noted that the

cables

34 and 35 are wound in opposite directions around the. reel 36 so that rotation of the reel in either direction by the motor 37 will cause one of the cables to be unwound from the reel while the other cable is wound onto the reel. Rotation of the reel 36 in opposite directions, therefore, will move the carriage 32 and its bucket 33 in opposite directions along the guideway 29 between its loading point adjacent the hopper 20 and a preselected discharge point above the bins 28, as will be later described.

Referring now to Figs. 1, 2, 4 to 8, inclusive, and 11 for a detail description of the dumping mechanism 42, it will be noted that the dumper is provided with three longitudinally spaced transversely extending

axles

105, 106 and 107, each having a pair of wheels 108 mounted on its opposite end portions for supporting the dumper on the rails 54 of the guideway 31. The rear axle 105 and middle axle 106 are rigidly connected to each other by side plates 109, the upper edges of which are flanged to provide camming surfaces 111 in longitudinal alinement with the follower rolls 87 which depend from the bottom of the bucket 33. The camming surfaces 111 are inclined from the rear end portion of the dumping mechanism 42 so that movement of the follower rolls 87 along the camming surfaces will effect gradual tilting of the bucket 33 relative to its carriage 32 as the bucket moves into its dumping position. The front axle 107 and middle axle 106 are connected by side bars 112 of sufficient length to permit pivotal movement of the bucket 33 into the space between these two axles, as will be later described.

Extending transversely between the side plates 109 adjacent the middle axle 106 is a base plate 113, see Fig. 6, upon which is mounted a bracket 114 on which is journaled a concave roller 115 that supports the cable 34 to prevent engagement between the cable and any portion of the dumping mechanism 42. Plates 116, mounted in closely spaced relationship with the side plates 109 at each side of the dumping mechanism 42, cooperate with the side plates to support the rollers 117 adjacent the camming surfaces 111. Roller mounting brackets 118 extend forwardly from the plates 116 and side plates 109 and are provided with rollers 119 at their outer end portions. The

rollers

117 and 119 engage and support the skip bucket 33 as it moves out of its dumping position.

Extending rearwardly from the base plate 113 and supported by a bracket 121, mounted on one of the side plates 109, is a switch mounting base 122, best illustrated in Figs. 5 and 6. Mounted on the base 122 longitudinally spaced relationship are a pair of two-

way toggle switches

123 and 124. The toggle arm 125 of the switch 124 is arranged in longitudinal alinement with a switch actuating finger 126 mounted on the leading end portion of the bail 57 to move the toggle arm between its two positions as the carriage 32 approaches and moves away from its dumping position. The toggle arm 127 of the switch 123 is positioned in alinement with a switch actuating finger 128 mounted on the inner channel beam 59 at the trailing end portion of the carriage body 56, so that the arm will be moved between its two positions by movement of the carriage 32 into and out of its dumping position.

As illustrated in Figs. 1 to 5, inclusive, 11 and 14, the dumping mechanism 42 is movable to any preselected position above the bins 28 by means of

cables

44 and 45 attached, respectively, to the front axle 107 and rear axle of the dumping mechanism. The cable 44 extends forwardly to the pulleys 131 which are mounted on the frame 89 in edge-to-edge relationship and are spaced from each other so that the cable, making a quarter turn around each of the pulleys, will extend rearwardly alongside the guideway 31 where it is supported at spaced points by the skid plates 53 and is connected to the reel 132 of the winch 43.

As is best illustrated in Figs. 2 and 3, the cable 45 extends rearwardly from the axle 105 to a pair of guide pulleys 133 which are mounted in spaced edge-to-edge relationship on the frame 134 so that the cable may be passed one quarter of a turn round each of the pulleys and returned along the guideway 31 to the reel 132. The frame 134 is mounted for longitudinal movement relative to the guideway 31 and is urged in a direction to maintain tension in the

cables

44 and 45 by springs 135.

The

cables

44 and 45 are fastened to and are wound in opposite directions around the reel 132 so that rotation of the reel in either direction will cause one of the cables to be unwound from and the other cable wound onto the reel to effect movement of the dumping mechanism 42 in the corresponding direction, see Figs. 3 land 14. The reel 132 forms a part of the winch 43 and is rota-ted by a driving gear 136 which meshes with a mating gear 137 rigidly connected to the axle upon which the reel is mounted. The driving gear 136 is manually opera-ted by means of a crank 138. A walkway 139 is provided alongside the winch 43 to provide access to the winch opera-ting crank 138.

Referring now to Figs. 1, 9 and 10 for a detail description of the loader 34 and the manner in which it automatically operates 'to load the bucket 33, it will be noted that the discharge opening of the hopper spout 23 is arcuate in side elevation and is directed toward the guideway 29. Mounted for pivotal movement about the axis 141, the loader 24 is provided with an arcuately formed wall 142 having a radius of curvature slightly greater than that of the discharge opening in the spout 23 so that pivotal movement of the loader will move the arcuate wall into and out of closing relationship with the discharge opening of the spout. The loader 24 is urged into the position in which its wall 142 closes the discharge opening of the spout 23 by a counterweight 143. Extending radially from the free, transverse edge of the curved wall 142 of the loader 24, and movable with the latter, is :a chute 144 which is movable into and out of alinement with the spout 23 when the loader 24 is pivoted to open and close, respectively, the spout discharge opening. It will be noted, from the broken line illustration of Fig.9, that when the loader 24 is pivoited into its position for closing the discharge opening of the spout 23, the chute 144 is spaced from the guide- Way 29 a sufficient distance to permit passage of "the bucket 33. Mounted on each side of the chute 144 and extending longitudinally thereof are the two angle irons 145 Which project outwardly from the sides of the chute into 'alineme-nt with the paths of movement of the-rollers 82 on the bucket 33.

As is best illustrated in Fig. 9, when the carriage 32 and bucket 33 move toward the loading point for the bucket, the rollers '73 projecting from the sides of the bucket, pass under the keeper bars 146 which are mounted on the rails 47 on opposite sides of the guideway 29. "The rollers 78, by-engagement with the keeper bars 146, will prevent pivotal movement of the bucket 33 during the loading thereof.

As the bucket 33 moves into its loading position, its rollers 82 are moved into "engagement with the angle irons 145, which are fastened to the sides "of the discharge chute 144, to efiect pivotal movement of the loader from its position for closing the discharge spout 23 to a position at which the chute extends into the opening of the bucket 33 and is in alinement with the spout 23. In this position of the loader 24, material will flow from the hopper 20 through its spout 23 and the chute 144 into the bucket 33. When the bucket has been filled, material will accumulate in the chute 144 and the flow of material, therefore, will be stopped. Subsequent movement of the bucket 33 upwardly away from its loading point will move the wear straps 83 on the bucket into engagement with the bottom of the chute 144 to cause the loader 24 to be pivoted into its position for closing the discharge spout 23. The loader will be maintained in this position by the counterweight 143 until the bucket again is returned to the loading point.

Referring now to Figs. 11 to 13, inclusive, for a detail description of the electrical circuits and the various elements that are connected therein for controlling the operation of the skip hoist,

limit switches

149 and 151 are positioned above and below, respectively, the counterweight 96 to stop the hoist motor 37 in the event either of the cables '34 or 35 breaks, the skip bucket 33 become jammed, or any other condition occurs which will cause excessive movement of the counterweight in either vertical direction. Manual control of the skip hoist operations is provided by a push-button station which is preferably located near the loading point for the skip bucket 33 and includes a switch butt-on 153 for stopping operation of the hoist motor 37, a switch button 154 for starting movement of the skip bucket in a downward direction and a switch button 155 for starting movement of the skip bucket in an upward direction.

Mounted adjacent the motor 37 is a combined plug switch and latching coil 156. The plug switch portion functions to apply a plugging or reversing current to the motor 37 when the skip bucket 33 reaches its discharging position to quickly stop the motor and prevent the bucket from coasting into engagement with the front axle 1107 of the dumping mechanism. The latching coil portion "holds the plug switch in its open position when the electrical supply circuits to the motor 37 are open to prevent accidental closing of the plug switch and consequent closing of the supply circuits by, for example, manual adjustment or servicing of the skip hoist. T he plug switch is of a conventional type and is drivingly connected to the motor 37 by a chain 157, or the like, so that the switch will be closed by operation of the motor 37 in a direction to move the skip bucket 33 toward its discharge point. Operation of the motor 37 in the opposite direction, however, will not effect closing of the plug witch and the switch is automatically moved to an open position when-the motor is at rest.

A solenoid operated brake 158 is mounted adjacent the motor 37 and is actuated "by opening of the electrical supply circuits to the motor to apply a frictional braking force'to the motor shaft.

A rotary drum or cam type switch 159 is drivingly connected to the shaft of the reel 36 by a chain 161, or the like, so that rotation of the reel in opposite directions to move the skip bucket 33 between its discharge and loading positions will effect oscillatory movements of the switch cams. The oscillatory movements of the switch cams will in turn effect controlled operation of the switches associated with the cams to decelerate and stop the motor 37 when the skip bucket 33 is moved to within a given distance of and arrives at, successively, its loading point and to accelerate the motor 37 when the skip bucket is moved 'a given distance away from its loading point. The relative positions of the cams and their associated switches will be more fully described in connection with the branch circuits with which they are associated.

Referring now to Fig. 12 for a detail description of the manner in which the various control elements are electrically connected and function to control operation of the skip hoist, it will be noted that the windings of the motor 37 are supplied with electrical energy through a three line, three-phase power circuit. Of the three lines, L1, L2 and L3 of the power circuit, lines L2 and L3 are 'each provided with a contactor U. A contactor D is connected between the input side of each contactor U and :the output side of the other contactor U so that alternate opening and closing of the pairs of contactors U and D will reverse the phase relationship of lines L1, L2 and L3 and will thereby reverse the direction of rotation of the motor 37.

On the motor side of the contactors U and ,D the lines L1, L2 and L3 are each provided with a contactor S. Lines L1 and L3 then pass through the coils R of a thermal overload relay and'are connected to taps T1 and T3, respectively, of the motor 37. The line L2 extends directly from the motor side of the contactor S to the tap T2 of the motor. Branch lines BL1, BL2 and BL3 are connected between points in the lines L1, L2 and L3, respectively, on the input side of the contactor S, and the taps T4, T5 and T6, respectively, of the motor 37. Each of the lines BL1, BL2 and BL3 is provided with a contactor H and coils R1 of a thermal overload relay are positioned in the lines BL1 and BL3 between the contactors H and the motor taps T4 and T6, respectively. An additional pair of contactors H1 are connected between the taps T1 and T3 and between the taps T1 and T2. The windings of the motor 37 are so connected to the terminals T1, T2, T3, T4, T5 and T6 that opening of the contactors S and closing of the contactors H and H1 will provide full speed operation for the motor 37 and closing of the contactors S and opening of the contactors H and H1 will provide half speed operation of the motor.

The solenoid brake 158 is connected between lines L2 and L3 on the output side of the contactors U and D so that when both pairs of contactors are opened the solenoid of the brake will be (lo-energized and the brake will be applied to stop rotation of the hoist motor 37.

Latching coil 156a of the plug switch 156 is similarly connected between lines L2 and L3 so that the plug switch 156 will be held in its open position while the contactors U and Dare open.

As illustrated in Fig. 12, the control circuit is made up of a plurality of branch circuits A, B, C, E, F and G, all of which are connected in parallel relationship between lines L1 and L3 of the power circuit.

Branch circuit A functions to control actuation of the skip hoist motor 37 and is made up of ,series connected thermal overload relay switches Aa and Ab that are opened by heating of the coils R1 and R, respectively, in the powericireuit when .an excess current is applied to the motor 37; relay coil Ac of an undervoltage protection deampere vice; and switches Ad and Ae that are manually operated by the

push buttons

155 and 153, respectively, at the push button station. A switch A which is manually operated by the push button 154 at the push button station, and a contactor Ag, that is closed by energization of the relay Ac of the undervoltage protection device, are connected in parallel with the switch Ad.

Branch circuits B, C and E of the control circuit are each connected to line L1 of the power circuit through a contactor Ba that is closed by energization of the relay Ac. Connected in series in the circuit B are an operating relay Bd for closing the contactors U when energized; switch Be, the operation of which will be later described; switch 149, opened by excessive movement of the counterweight 96 in an upward direction; switch Bd that is closed by energization of the relay Bb; and switch Be, which is the normally closed side of the two-way toggle switch 123 on the dumping mechanism 42. The switch Be is moved to its open position by movement of the skip bucket 33 into its dumping position. A timer switch B the operation of which will be later described, and a manually operated switch Bg, that is connected for operation with the switch Ad by the push button 155, are connected in parallel with the switch Bd.

Connected in series in the branch circuit C of the control circuit are an operating relay Ca for closing the contactors D and opening the switch Be when energized; switch Cb, opened by energization of the relay Bb to prevent closing of the circuit C while the circuit B is closed; a cam operated switch Cc of the cam switch 159; limit switch 151, that is opened by excessive travel of the counterweight 96 in a downward direction; and a manually operated switch Cd, that is connected for operation with the switch A) by the push button 154. The cam for operating the switch Cc is adjusted for oscillation through an angle of less than 360 by rotation of the reel 36 to move the skip. bucket between its loading and discharge positions. It will be appreciated that the end point in the oscillatory movement of the cam which corresponds with the discharge point of the bucket 33 will vary in accordance with the position of the dumping mechanism 42. The end point in the oscillatory movement of the cam which corresponds with the loading point of the bucket 33, however, is fixed and the cam is adjusted to open the switch Cc only when it has reached this end point. For reference purposes, the end point of the movement of the cam at which the switch Cc is opened has been indicated as being at in Fig. 12. An operating relay Ce for the timing switch B is connected in parallel with the relay Ca and functions to effect closing of the switch B after the elapse of a given time interval,

when the flow of current through the branch circuit C is interrupted. The relay Ce also eifects opening of the switch Bf immediately upon closing of the branch circuit C. A switch Cf, operated by the relay Ca, and a timer switch Cg are connected in series with each other and in parallel with the switch Cd. A second timer switch Ch is connected in parallel with the switch Cd and plug switch 156b is connected in parallel with the switch Cd and limit switch 151.

Connected in series in the branch circuit E of the control circuit are a timer operating relay Ea and a timer switch Eb. A switch Ec, which is the normally open side of the toggle switch 123 on the dumping mechanism 42, is connected in parallel relationship with the timer switch Eb. The switch E0 is closed by movement of the skip bucket 33 into its dumping position at the same time that the switch Be is opened. The timer operating relay Ea controls operation of the timer switches Eb, Cg and Ch. The manner and sequence of operation of the timer switches Eb, Cg and Ch by the relay Ea will be described as follows:

The branch circuit E is normally open andis closed by movement of the carriage 32 into its position for dumping the bucket 33 to actuate the two-way toggle switch 123- and to close the switch Ec. Upon closing of the circuit E, the relay Ea is energized to efiect instantaneous clos ing of the switch Eb and instantaneous opening of the switch Cg. After a predetermined time interval of, for example, eight seconds, the relay Ea will effect closing of the switch Ch and will simultaneously open the switch Eb and close the switch Cg. The branch circuit E is subsequently opened by movement of the carriage 32 to return the toggle switch 123 to its position for opening the switch Ec whereupon the relay Ea is de-energized and will etfect movement of the switch Ch into its normally open position.

Connected in series in the branch circuit F are an operating relay Fa which, when energized, closes the contactors S in the power circuit for half speed operation of the motor 37; switch Fb which is opened by actuation of the branch circuit G, as will be later described; switch Fc, which is the normally open side of the two-way toggle switch 124 on the dumping mechanism 42; and switch Fe which is closed by energization of the relay Bb. The switch Fe is closed when the carriage 32 approaches to within a given distance of the dumping position and actuates the toggle switch 124 on the dumping mechanism 42. Connected in parallel with the switch Fe is a cam operated switch Ff of the cam switch 159. The cam associated with the switch Ff is mounted for oscillatory movement with the cam associated with the switch Cc and is adjusted to close the switch Ff when oscillated to within 12 of the 0 end point in the movement of the cams. At this 12 position of the cams, the skip bucket 33 will have a corresponding position at a given distance from its loading point.

Connected in series in the branch circuit G of the control circuit are an operating relay Ga which, when energized, closes the contactors H and H1 of the power circuit for fullspeed operation of the motor 37 and for closing the switch Fb in branch circuit F; switch Gb that is opened by energization of the relay Fa; cam operated switch Gc of the camming switch 159.; switch Ge which is the normally closed side of the two-way toggle switch 124 on the dumping mechanism 42; and switch G that is closed by energization of the relay Ca.

The switch Ge is opened when the switch Fe is closed and both switches are returned to their normal positions by movement of the carriage away from the dumping position for a sutficient distance to actuate the toggle switch 124 on the dumping mechanism 42. The branch circuits F and G are connected to each other to provide a common path through either of the switches Fe or G so that closing of either switch Fe or G by actuation of its operating relay Bb or Ca, respectively, will permit the circuit F or G to be closed. When both of the switches Fe and 6 are open, neither of the circuits F or G can be closed. The cam associated with the switch is movable with the cams of the switches Cc and Ff and is adjusted to open the switch Gc when the cams are oscillated to within the aforementioned 12 of the 0 end point in the movement of the cams. In other words, the switch 60 is opened and closed when the switch F f is closed and opened, respectively.

The operating relay Bb, in addition to controlling operation of the contactors U, controls operation of the switches Bd, Cb and Fe, as described above. These switches are so connected for operation by the relay Bb that closing of the contactors U in the power circuit will necessarily eifect opening of the switch Cb and closing of the switches Ed and Fe and, conversely, opening of the contactors U will efiect closing of the switch Cb and opening of the switches Ed and Fe. The switch Cb, therefore, provides an electrical interlock between the branch circuits B and C so that the branch circuit C cannot be closed while the branch circuit B is closed.

The operating relay Ca, in addition to controlling the position of the contactors D of the power circuit, controls the positions of the switches Bc, Cf and 6 These switches are so connected for operation by the relay Ca that-when the relay is actuated to close the contactors D, the switch Be is opened and the switches C7 and Gf are closedand, -conversely,'when the contactors D are opened, the switch B is closed and switches 'Cf and G1 are opened. A second electrical interlock is thereby provided between the branch circuits C and B by the switch Bcwhich will prevent closing of the circuit B when the circuit C is-closed.

Considering now the functions of the branch circuits A, B, C, E, F and 'G in controlling operation of the skip hoist, the branch circuit A permits the automatic operation of the skip hoist to be either stopped at the will of the operator or started with the initial movement of the skip hoist bucket 33 either in an upward or a downward direction; and it prevents operation of the skip hoist when the line current is reduced to a value below that at which proper operation can be carried out and .stops operation of the skip hoist when the current applied to the-motor 37 exceeds a safe operating value.

The means for carrying out the above described functions of the branch circuit A will be described as follows:

The manual stopping of the operation of the skip hoist is effected by the switch Ae which, when opened by the push button 153, will interrupt the branch circuit A and de-energize the relay Ac of the undervoltage protection device to effect opening of the contactors Ag and Ba. Subsequentrelease of the push button 153 will permit the switch Ae to close but the branch circuit A will remain open due to the open condition of the contactor Ag and the normally open positions of the switches Ad and A Manual starting of the automatic operation of the skip hoist may thereafter be initiated in the desired direction by operation of the push button 155 to start movement of the skip bucket 33 in the upward direction or by operation of the push button 154 to start movement in the downward direction. Operation of the push button 155 will close the switch Ad to close the branch circuit A and energize the relay Ac. The relay Ac will'thereupon close the contactors Ag and Ba so that subsequent release of the push button and opening of the switch Ad does not interrupt the circuit A which remains closed through .the contactor Ag. Operation of the push button 155 also etfects closing of the mechanically connected switch Bg to close the branch circuit B, as will be later described.

It, alternatively, the push button 154 is operated to close the switch A the branch circuit A will remain closed through the contactor Ag after release of the push button 154, as described above, andthe switch Cd will be operated by the push button to effect closing of the branch circuit C, as will be later described.

in the event that insufficient current is applied to the lines L1, L2 and L3 for proper operation of the skip hoist, the relay Ac will effect opening of .the branch circuits A, B, C, and E by opening the contactors Ag and Ba.

Thermal overload relay switch A'b is opened by the application of excess current to the .coils R of its operating relay when the motor is operating at half speed and thermal relay switch Aa is opened by the application of excess current to the coils R1 inthe branch lines .BLl and 3L3 when the motor is operating at full speed.

Assuming that the automatic operation of the skip hoist has 'been initiated by the operation of the push button 155 to close the switch Bg, the branch circuit B will be closed through the switch Bg, the normally closed switch Be, the normally closed limit switch 149 the switch Bc which is closed by the deenergized condition of the relay Ca in branch circuit C, and the operating relay Bb. The relay *Bb, therefore, will beenergized to close the switch Br! and Fe and the'contactorsU in the power circuit and to openthe switch Cb. "The branch circuit '13 will remain closedthrQugh-thesWitch Bd after release .of the push button 155 to open the -'switch*Bg and athe contactors U, :being closed, will cause operation of the motor 37 in adirection .-to move :the skip "

bucket

3,3 upwardly. Movement of the skip bucket 33 in an upward direction will continue until the bucket reaches its dumping position and the two-way toggle switch 123 is actuated to open the switch Be in the branch circuit B. At this time the switches Ed and Fe will be opened and the switch Cb will be closed by deenergization of the operating relay Bd so that subsequent return of the switch Be to its normally closed position cannot reclose the branch circuit B.

At the same time that the switch Be is opened by movement of the skip bucket 33 into its dumping position to actuate the toggle switch 123, the switch Ec will be closed to complete the branched circuit E and to energize the operating relay Ea for the timing switches Eb, Cg and Ch. As was previously described, the switch Eb will be instantaneously closed by energizationof the relay Ea and the switch Cg will be instantaneously opened. At the same time that the branch circuit E is closed by closing of the switch BC, the branch circuit C will be temporarily closed through the plug switch 156b, the cam switch Cc and the switch Cb which is closed by deenergization of the relay Bb. The relay Ca, therefore, is temporarily actuated to close the contactors D in the power circuit and .to thereby apply a plugging or reversed current to the motor 37 and immediately stop rotation thereof. When the rotation of the motor 37 ceases, the plug switch 156b automatically opens to break the branch circuit C and the skip bucket 33 will remain at rest in its dumping position. Energization of the branch circuit ,E and the relay Ea, however, will, after a predetermined time interval of, for example, 8 seconds, cause the switch Ch to close and complete the branch circuit C at which time the relay Ca is again energized to close the contactors D in the power circuit. The timer switch Cg ,is .closed at the same time that the timer switch Ch is closed so that energization of the rel y Ca to close the switch Cf will establish ,a closed circuit through the switches Cg and C to prevent reopening of the circuit when the timer switch Ch is subsequently returned to its normal open position. The branch circuit E is opened when the branch circuit C is closed through switches Cg and C3 by opening of the timer switch Eb and by movement of the skip bucket 33 in a downward direction to return the switch E0 to its normally open position.

After the above described reversal in the direction of movement .of the skip bucket 33 at its dumping position, the bucket will continue to move in a downward direction until it reaches the loading position at which time the cam switch 159 will have been rotated to efiect opening of the switch .Cc to break the branch circuit C. The operating relay Ca thereupon will be de-en rgized :to effect opening of switches Cf an-d-Gf and the contactors D in the power circuit and closing of the switchzBc. When the contactors ,Dare opened, the solenoid brake 158 will be .de-energized to apply a braking action on the shaft of the motor 37. At the time the branch circuit ,C is broken, the operating coil Ce will also be deenergized to effect, after a predetermined time interval, closing of the switch Bf to close the branch circuit Band initiate movement .of the skip bucket 33 in an upward direction. The upward and downward movements of the skip bucket will thereafter be automatically repeated until the branch circuit A is interrupted by the contactor or any-of the switches connected therein.

Initiation of automatic operation of the skip bucket .33 in a downward direction by operationof the .push button 154 will effect the same cycle as described above with the exception that the initial movement will beina downward direction .due to the closing of the switch 16d .to energize the operating ,relay .Ca and toclose ,the contactors D in the power circuit. The switch Cf is :closed by energization of the relay Ca so that subsequent release of the push .:button 154 -.will not'interrupt the'branch circuitC.

The functionof the branch circuits "F and G is to re- '13 duce the speed t movement of the skip bucket 33 as it approaches and departs from its dumping and loading positions. Considering first the condition of the branch circuits F and G as the skip bucket approaches its dumping position and before the switch 124 on the dumping mechanism 42 has been actuated by the carriage 32, the switches Fe and F are both in their open positions so that the operating relay Fa is de-energized. The switch Fe is closed by energization of the operating relay Bb and the switch G is opened by de-energization of the operating relay Ca. The switch Fb will be open due to energization of the relay Ga and the switch Gb will be closed by de-energization of the relay Fa, the two switches Pb and Gb providing an electrical interlock to prevent closing of both circuits F and G at the same time.

The branch circuit G is closed through the switch Fe, the normally closed switch Ge, the cam operated switch Ga and the interlock switch Gb so that the operating relay Ga is energized to close the contactors H in the branch lines BLI, BL2 and BL3 of the power circuit and the contactors H1 between their associated motor taps. The motor 37, therefore, is operating at full speed to move the skip bucket 33 toward the first switch 124 on the dumping mechanism 42.

When the skip bucket 33 has moved to a position at which the switch 124 is actuated, the switch Fe in the branch circuit F is closed and the switch Ge in the branch circuit G is opened so that the operating relay Ga is deenergized to open the contactors H and H1 and to close the switch Fb. The relay Fa is simultaneously energized to close the contactors S and to reduce by one-half the speed of rotation of the motor. The direction of movement of the skip bucket 33 is thereafter reversed as described above, with the switch Fe being opened and the switch Gf being closed by the reversal in direction of movement, and the skip bucket will move downwardly at half speed to a position for actuating the switch 124. When the switch 124 is actuated by downward movement of the skip bucket 33, the switch Fe is opened and the switch Ge is closed to interrupt the branch circuit F and to close the branch circuit G so that the contactors S and H will be moved into their opened and closed positions, respectively, by de-energization of the operating relay Fa and 'energization of the relay Ga.

The reduction in the speed of movement of the skip bucket 33 as it approaches and departs from its loading position is controlled entirely by the cam switch 159 through its switches F and Ge. In other words, when the skip bucket 33 approaches to within a given distance of its loading point at which the cams associated with switches Ff and G0 are moved to within 12 of the 0 end point in their movement, the switch F is closed by its associated cam and the switch G0 is opened by its associated cam to close the branch circuit F and to open the branch G, respectively. The skip bucket 33 will thereafter continue to move at its reduced speed to a point at which the rotation of the cam associated with the switch Cc will open the branch circuit C to stop movement of the skip bucket. Upward movement of the skip bucket 33 is, after a predetermined time interval, automatically initiated as described above, and when the skip bucket has again reached the point at which its speed of approach was reduced, its speed of movement will be increased by movement of the cams associated with the switches Ff and G0 to their aforementioned 12 positions to open the switch Ff and close the switch Gc whereupon the contactors H are closed and the contactors S are opened as described above.

It is to be understood that the form of this invention herewith shown and described is to be taken as a preferred example of the same, and that various changes in the shape, size, and arrangement of parts may be resorted to without departing from the spirit of the invention or the scope of the subjoined claims. I

14 Having thus described the invention, I claimi '1. A skip hoist for transferring material from a low level position to the elevated, horizontally spaced and alined top openings of a plurality of bins, or the like, comprising guide means extending vertically between the low level position and a level above the tops of said bins and then extending horizontally over said bins, a carriage mounted for movement along the vertical and horizontal portions of said guide means, a bucket mounted on said carriage for movement therewith and for pivotal movement relative thereto between a material receiving and conveying position and a material discharging position, means operable to move the carriage in opposite directions along the guide means between the low level position and the farthest removed of the bin openings, bucket dumping means movable in parallelism with the horizontal portion of said guide means to selectively position the dumping means relative to the top openings of the bins, said dumping means engaging the bucket for pivoting the bucket into its discharging position when the carriage moves into overlying relationship with the dumping means and for returning the bucket to its material receiving and conveying position relative to the carriage when the carriage is moved in a reverse direction out of said overlying relationship, and control means operatively connected to said carriage moving means and mounted on said dumping means for actuation by said carriage to control the movement of the carriage as it approaches, arrives at, and departs from said overlying relationship.

2. A skip hoist as defined in claim 1 further characterized by the bucket having an open upper end and lying in a plane paralleling the path of the guide means while arranged in its material receiving and conveying position, and a gate fixed on the carriage for covering a portion of said open end of the bucket to prevent spillage of material While the bucket is moved along the horizontal portion of the guide means.

3. A skip hoist as defined in claim 2 further characterized by means associated with the bucket and the gate on the carriage for stopping pivotal movement of the bucket when it reaches its discharging position.

4. A skip hoist as defined in claim 2 further characterized by the carriage comprising a body having two wheel mounting axles supporting its opposite end portions with the leading axle being rotatable, means mounting the intermediate portion of the bucket on the rotatable axle, a bail mounted at its trailing end portion on said rotatable axle and having a wheel mounting axle supporting its leading end portion, and means mounted on the leading end portion of the bail for covering a portion of the open end of the bucket to prevent spillage of material while the bucket is moved along the horizontal portion of the guide means.

5. A skip hoist as defined in claim 4,further characterized by the bucket having means projecting between the two axles of the carriage and engaging the said bucket dumping means for pivoting the bucket into its discharging position with its open upper end projecting into the space defined by the carriage bail.

6. A skip hoist as defined in claim 1 further characterized by the bucket dumping means comprising a wheeled body, a pair of rails for supporting said Wheeled body, and camming members mounted on the Wheeled body; said bucket having means engageable with said camming members for pivoting the bucket into its material discharging position as the bucket moves over said wheeled body in one direction, and said wheeled body having means engageable with the bucket for returning the latter to its material receiving and conveying position as the bucket moves over said wheeled body in the opposite direction. I

7. A skip hoist as defined in claim 1 further characterized by the carriage moving means comprising two cables fastened to the opposite ends of the carriage, a reel for winding up one of said cables while unwinding the other, a reversible electric motor for rotating said reel in opposite directions, and electric control circuits connected to said electric motor, and said control means comprising switches mounted on the bucket dumping means and connected in said motor control circuits, and means mounted on the bucket carriage for successively operating said switches to decelerate and stop the movement of the bucket carriage as the bucket reaches its discharging position and for reversing the direction of and accelerating movement of the bucket carriage after the bucket has been emptied.

8. A skip hoist for transferring material from a low level position to the top openings of a plurality of bins, comprising guide means extending vertically between said low level position and substantially the level of the tops of said bins and then extending horizontally above the bins, a carriage mounted for movement along the vertical and horizontal portions of said guide means, means for moving said carriage in opposite directions, a bucket mounted on said carriage for movement therewith and for pivotal movement relative thereto to discharge the material from the bucket into a preselected one of said bins when positioned on said horizontal portion of said guide means, means on said carriage for retaining material in said bucket while the latter is moving along said horizontal portion of the guide means to said preselected bin, discharge means movable in parallelism with said horizontal portion of the guide means into a position above said preselected bin, means carried by said bucket for engaging said discharge means to effect the discharging movement of the bucket, means mounted on said discharge means and actuated by the carriage for controlling the carriage moving means to decelerate the carriage as the bucket approaches the discharge location and, after the bucket has been discharged, to stop the carriage and reverse its direction of movement, and means for controlling the carriage moving means to decelerate and stop the carriage as the bucket is moved into the low level position and to thereafter reverse the direction of movement of the carriage.

9. A skip hoist as defined in claim 8 further characterized by said carriage having longitudinally spaced means for successively actuating the said control means that is mounted on the discharge means to bring about deceleration of the carriage before the bucket is discharged and to stop the carriage after the bucket is discharged.

10. A skip hoist as defined in claim 8 further characterized by said carriage moving means comprising cables attached to opposite ends of the carriage, means for actuating said cables in reverse directions, a prime mover drivingly connected to said cable actuating means, and means operatively connecting said prime mover and the said control means mounted on the discharge means to permit automatic control of the prime mover at all positions assumed by the movable discharge means.

11. A skip hoist as defined in claim 8 further characterized by a prime mover .drivingly connected to .said carriage, and .the first mentioned control means comprising a stitch actuated by said carriage when the bucket is at a given distance from its discharge point to reduce the speed of said prime mover as the bucket approaches said point and to increase the speed of the prime ,mover as the bucket moves away from said point, a second switch actuated by saidcarriage when the bucket-reaches its discharge point to stop said prime mover, and artiming device which starts the prime mover in .a reverse direction after a predetermined time interval during which the bucket isldischarged.

12. A skip hoist as defined in claim 8 further ,characterized by a prime mover for said carriage, and the last mentioned control means comprising a sWiICh .drivingly connected to the prime mover for reducing the speed .of the latter when the bucket is moving in either direction 16 within a given distance of its low level position and for stopping said prime mover when the bucket reaches its aforesaid low level position, and a switch actuated by movement of the bucket into its low level position for starting the prime mover in a reverse direction after a predetermined time interval.

13. A skip hoist as defined in claim 8 further characterized by said carriage having cables attached thereto for moving the carriage along said guide means, a rotatable reel associated with said cables for moving the cables and the carriage attached thereto, a prime mover drivingly connected to said reel for rotating the latter, means associated with said carriage for actuating said movable control means when the carriage is moved into a given relationship with said discharge means, and means associated with said reel for actuating said second mentioned control means when the rotation of said reel has caused the cables to move the carriage and the bucket mounted thereon into a given relationship with the low level position of'the bucket.

14. A skip hoist for transferring material from a low level position to a plurality of bins, comprising guide means extending substantially vertically from the low level position and substantially horizontally above the bins, discharge means mounted for movement to preselected points along the substantially horizontally extending portion of said guide means, a carriage movable along said guide means, an electric motor for moving the carriage in opposite directions along said guide means betweensaid low level position and a discharge point at said preselected'position of the discharge means, an elongated bucket mounted forpivotal movement on said carriage between a balanced position at which the bucket rests against the carriage and a tilted discharge position, a gate mounted on said carriage for substantially closing said bucket in its balancedposition, means mounted on the bucket for movement into engagement with said discharge means to effect pivotal movement of the bucket into its tilted discharge position, a pair of switches mounted on said discharge means, one of said switches being actuated by said carriage at a given distance from said discharge point to decrease and increase the speed of the electric motor as the carriage approaches and departs from, respectively, the discharge point and the other of said switches being actuated by said carriage at said discharge point to stop said motor, first .timing means for starting said motor in a direction to move the carriage away from said discharge point after the bucket is discharged, switch means operated in synchronism with said motor for decreasing the speed of said motor while said carriage is within a given distance from said low level position and for stopping said motor when the carriage is moved to said low level position, and second timing means for starting said motor in a direction to move said carriage away from said low level position.

15. A skip hoist as defined in claim 14 further characterized by said first timing means including a relay operated by actuation of said other of said switches, and a switch operated by said relay in timed relationship with actuation of said other of said switches to delay starting of said'motor until after the bucket is discharged, and said second timing means including a relay operated by stopping of said motor at said low level position and a switch operated by the relay in timed relationship with the stopping of the motor.

16. A skip hoist as defined'in claim 14 further characterized by a switch closed by rotation of said motor in a direction to move the carriage towards its discharge position and opened by the stopping of the motor, the closed position of the switch supplying a reversing current to the motor to effect immediate stopping of the latter when said other of-said'switches is actuated.

17. A skip hoist as defined in claim l4 further characterized by said discharge means including means for engaging said bucket to return the latter from its tilted to its 17 balanced position as the carriage moves away from the 637,716 discharge point, and means for maintaining the bucket 985,398 in its balanced position at the low level position. 1,015,251 1,333,947 References Cited in the file of this patent 5 2,599,444

UNITED STATES PATENTS 552,664 Hunt Jan. 7, 1896 54 91 118 Dodge Nov. 21, 1899 Cook Feb. 28, 1911 Schraeder Jan. 16, 1912 Travell Mar. 16, 1920 Gavin June 3, 1952 FOREIGN PATENTS Great Britain July 27, 1942