US1575687A

US1575687A - Jib crane

Info

Publication number: US1575687A
Application number: US586603A
Authority: US
Inventors: Hollick Frederick William
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 1922-09-07
Filing date: 1922-09-07
Publication date: 1926-03-09
Anticipated expiration: 1943-03-09

Description

March 9 1926.

. F. W. HOLLICK JIB CRANE Filed Sept. '7, 1922 3 Sheets-Sheet 1' INVENTOR.

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March 9 1926.

F. w. HOLLICK JIB CRANE Filed Sept. 7, 1922 3 Sheets- -Sheot 2 641* M ATTORNEYS.

March 9 1926. 1,575,687

F. W. HOLLICK JIB CRANE Filed Sept. '7, 1922 3 Sheets-Sheet 5 INVENTOR.

MMMKM qwdww -Patented Mar. 9, 1926.

UNITED "STATES PATENT OFFICE.

FREDERICK WILLIAM HOLLICK, OF GOUROCK, SCOTLAND, ASSINGNORTO THE BAB- COOK & WILCOX COMPANY, OF BAYONNE, NEW JERSEY, A CORPORATION OF NEW JERSEY.

JIB CRANE.

Application filed September 7, 1922. Serial No. 586,603.

To all whom it may concern:

Be it known that I FREDERICK WILLIAM HOLLICK, a subject of the King of Great Britain, residing at Gourock, in the county of Renfrewshire, Scotland, have invented certain new and useful Improvements in Jib Cranes, of which the following is a specification.

My invention relates to improvements in jib cranes which will be understood from the following description and the annexed drawings, in which Fig. 1 is an illustrative. embodiment of one form of crane embodying my invention, and Fig. 2 is an enlargement of a portion of Fig.

In the crane illustrated, a frame 10 sup ports the structure, this frame being mounted movably in the usual way. Since the particular mounting of the support for the crane is no part of my invention, detailed description thereof will be unnecessary to an understanding of my invention. On the frame 10 is a jib 11 pivoted at 12 in the usual manner. I

The angular inclination of the jib 11 is controlled by a sector arm 13 pivoted at 14 on the framework of thecrane, the sector 13 having one of its arms connected by a link 15 with the crane 11. The periphery of the sector is provided with gear teeth 16 which are engaged by the teeth of a gear 17 connected by a bevel gear 18 driven by a bevel pinion 19 on the upper end of the shaft 20 supported in the crane frame. The lower end of the shaft 20 is provided with gearing 21 by which the shaft may be driven through a motor 22. At the upper end of the jib is a lever arm 23 pivoted at 24 on the jib and carrying on its outer end suitable pulleys, as 25 and 26, by which the cables or ropes 27 and 28 for lifting the load may be passed from the load-to the winding mechanism on the crane frame.

As a means for counterbalancing the crane against the load, I provide a tank or receptacle which may be filled with any suitable liquid or granular material in order to provide the necessary counterbalance weight, and in order that thischaracter' of weight may not spill, I support the receptacle 29, as at 30, on the ends of a pair of two-armed levers. 31 which are pivoted at 32 on the crane frame 10. These arms are connected by the rod 33 with the sector 13 by a pivot joint, as at 33, so that as the sector 13,is

turned to raise and lower the jib, and thereby decrease or increase the moment of the load,'the arms 31 are correspondingly swung to shift the position of the weighted receptacle 29, and at the same time, by reason of the pivotal connection of this receptacle with the arm 31, the receptacle itself will remain upright in all positions. By providing an arrangement, such as that described, the amount of weight necessary to counterbalance the load can be readily changed by tilting the receptacle and pouring out some of the liquid or granular material if the counterbalance is heavier than the load required, and similarly additional material readily weight.

As a back guy to control the action ofthe j1b arm 23 and also to assist in carrying 9 available at the points of use of the crane may be used to increase the counterbalance the load directly to the crane frame, I provide a guy 34 which preferably will be of steel cable which is connected to the crane frame in a manner to be described more fully hereinafter and which passes over a circular guide 35 formed as part of the lever 23, and preferably is attached near the outer end of the lever 23. The back guy 34, as shown best in Fig. 2,'is connected to a yoke 35, the legs of which'extend through a plate or plates 36 held to the legs of the yoke and a spring 37 is interposed between the plate 36 and the member 38 ofthe crane frame. l/Vith the construction described, the sudden application of a load to the end of the arm 23 willbe transmitted through the back guy 34 and will be taken up through the spring 37, so as to absorb any shock to prevent the breaking of the back guy 34. The back guy 34 passing over the guide 35 will permit the I outer end of the arm 23 to lower as the jib is raised to a vertical position to swing the load inward so that the clearance height of the upper end of the jib remains more nearly constant that would be the case if the arm 23 were rigidly connectedto the jib 11. At the same time, the back guy 34 prevents the arm 23 from turning around the pivot 24 when the weight is applied to the outer end of the arm.

In the illustrative form, the crane is provided with a single and also a multiple hoisting rope, the single rope 27 passing over the pulley 25 and a corresponding pulley on the pivot 24 directly to the hoist ing mechanism on the crane. The multiple hoisting rope 28 has one end attached to the lever 42 pivoted on the crane frame in the manner to be described more fully hereinafter and from thence it passes over an idler on the pivot 24c and to and around a loose pulley 26 on the pivot 26. It then passes successively around pulleys in the hoisting block and on the pivot 26 as many times as desired and from the last pulley 393 on the pivot 26 over a loose pulley 394 to the hoisting drum 4-0, the standing or stationary portion of cable 28, as well as the moving portion, being indicatedat- 39. In order that the standing and moving portions of this multiple cable shall not be shifted relatively when the load is to be shifted by the raising or lowering of the jib, I pass the standing portion 39 of the rope around the pulley 391 which is concentric with the hoisting drum around which the moving portion of the cable extends and attach the'end of this standing portion 39 to a point 43 on a lever 42 which is pivoted at at on the crane frame. Since the standing and moving portions of the multiple hoisting rope extend between substantially the same points, it is obvious that the raising and lowering of the jib will not affect the relative positions of these cables to cause a raising or lowering of the load by reason of this relative movement,

which would be obtained if the standing end 39 were connected directly to the frame of the crane so as not to be parallel at all times to the moving portions.

The outer end of the lever 42 is carried on a spring 45 having its lower end against a seat 46 connected to the crane frame. An increase of load on the multiple cable hoist will be transmitted through the cables Y28 and the standing end'39 to the lever 42 and will be resisted by the spring 45. Nevertheless, the spring 45 will be compressed in accordance with the load on this portion of the hoist, so that the lever 42 will vary in its angular position around the center 4-4 in accordance with the load being lifted.

On the vertical shaft 20, which rotates the jib sector 13, I provide a screw thread and on this screw thread there is a nut 53 provided with suitable guides to preventits turning with the shaft 20, sothat as the shaft 20 is rotated, the nut 53 will move up or down in accordance with the direction of rotation. The position of the nut 53 will therefore always have a predetermined relation with the angular position of the jib 11.

In the illustrative embodiment, I mount on the arm 42 a switch box 55 having an arm 56 projecting into the path of an arm on the nut 53. The winding drum for the hoisting ropes is provided with a gear 41 driven by gears 4:7 and 18- from the motor pinion 49 on the motor 50. This motor may be provided with an electric brake 51 an d the motor 22 with an electric brake The switch box 55 is connected by suitable wiring with the motors 51 and 52, so that when the arm 56 of the switch box is rotated by contacting with the arm 54 of the nut 53, the power to the

motors

52 and 22 is shut off and the magnetic brakes applied.

It will be obvious by an inspection of Fig. 2 that the arms 56 and 54 will be moved toward each other either by an increase of the load on the hoist, which is transmitted through the standing end, 39 to the lever 42 carrying the switch box 55, or by the rotation of the shaft 20 in a direction to lower the outer end of the jib 11. The parts are so arranged, however, that the arms 56 and 5-1 will not contact when light loads are carried by the jib even when the jib is dropped to its lowermost position, which would be when the arms 13 and 15 are in a straight line.

If, however, the load being lifted is excessive, then the lever 42, and the arm 56 with it, will be pulled down, so that as the crane ll approaches its most nearly horizontal position, the arms 54. and 56 will contact to shut off the power and to apply the brakes. It will be seen that the arrangement provided is one which is calculated to prevent the crane overturning by providing a means for shuttin off the power when the moment of the loa exceeds a predetermined amount. Obviously this predetermined amount is a function of both the total load and the arm of that load which is its distance from the crane, and the device which I have provided operates when the moment of the load exceeds a predetermined amount, no matter whether that amount is made up of a very heavy load with a short arm or with a long arm and a lighter load.

It will be obvious that the embodiment of my invention may be varied within wide limits and it will be understood that the arrangement described is merely illustrative.

I claim 1. In a jib crane a load-lifting drum mounted on the crane frame, a pulley mounted coaxially with. the drum, a loadlifting rope passing from the drum to the end of the jib and the weight to be lifted and returning over the end of the pulley to and partially around said pulley and an chored to the crane frame, and means to change the inclination of the ib.

2. In a jib crane, a hoisting drum and power-actuated means to move it, power-actuated means to change the inclination of the jib, a hoisting rope having its movable end passing around the drum, a lever having the standing end of the hoisting rope connected thereto, resilient means to resist the turning of the lever by said rope, a control arm connected to and movable with said lever, and a contact piece connected to the jib and arranged to move therewith, saidcontrol arm and said contact piece being arranged to be moved toward each other either by an increased! pull on the standing end of the rope or by the motion of the jib toward the horizontal, said control arm being constructed and arranged to suspend the motion of said power-actuated means when the control arm is contacted by the contact piece.

3. In a jib crane, means to hoist a load comprising a hoist rope passing over the head of the jib and means to move the rope, a first movable member on the crane frame and connected to the standing end of the hoist rope, means to change the inclination of the jib, a second movable member arranged to be moved in accordance with the angular motion of the jib, said movable members being constructed and arrcnged to be moved toward each other by the motion of the jib toward the horizontal and by the increase in the weight on the hoisting rope, and means, actuated by the contact of said members, to suspend the operation on the hoisting means and the jib inclination changing means.

4:. In a jib crane, means to change the inclination of the jib, means to hoist a load on said jib, automatic means to suspend the rendered operative when said movable members occupy a predetermined relative position.

5. In a jib crane, means to change the inclination of the jib, means to hoist a load on said jib, and automatic means jointly controlled by the operation of the means for changing the inclination of the jib and of the load hoisting means to suspend the operation of both of said] means when the overturning moment of the load on the crane reaches a predetermined amount.

6. In a jib crane, an electric motor for changing the inclination of the jib, an electric motor for hoisting a load on'said jib, and means jointly controlled by the operation of the means for changing the inclination of the jib and of the load hoisting means for breaking the circuit to both of said motors, said jointly controlled means comprising a member which yields in accordance with the load.

FREDERICK WILLIAM HOLLICK.