US2722319A - Crane - Google Patents

Description

' Filed Sept. 19, 1950 A. s. STOKES 2,722,319

CRANE Nov. 1 1955 5 Sheets-Sheet 1 Attorney Nov. 1, 1955 A. s. STOKES 2,722,319

CRANE Filed Sept. 19, 1950 5 Sheets-Sheet 2 Inventor 4/v7-a/vy 56077 570x55,

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CRANE Filed Sept. 19, 1950 5 Sheets-Sheet 3 59N70/VY scan-aromas,

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CRANE Filed Sept. 19, 1 50 5 Sheets-Sheet 4 Inventor flA m/vy \scarr 67 01(56 MQQ Attorney United States Patent CRANE Antony Scott Stokes, Ipswich, England, assignor to Rausomes & Rapier Limited, Ipswich, England Application September 19, 1950, Serial No. 185,565

4 Claims. (Cl. 212-8) Cranes used for unloading ships at a dockside have often tooperate under cramped conditions and satisfy exacting requirements. Preferably they should be able to raise a load from the further side of a hold and lower it either as close as possible to the foot of the crane or at'the greatest possible distance from it in various directions. At the same time the jib must clear obstructions such as the rigging and near rail of a ship. Such cranes are sometimes carried on a'high gantry which runs on rails, but these are bulky, heavy and therefore more expensive to build than cranes with a jib mounted on a comparatively low and narrow base. The outwards derricking of a jib on a low base, however, is limited by obstructions such as the near rail of the ship and a good outreach can only be obtained with a jib that is either inconveniently long or is bent. A long-reaching jib is relatively heavy, slow in operation and difiicult to keep clear of rigging, as also is a permanently bent jib, which becomes undesirably twisted when being slewed, and neither can be derricked in as much as is desirable to allow a load to be dropped close to the base of the crane.

It is an object of the present invention to provide a crane with a jib which can be mounted on a low base and yet manoeuvred clear of obstructions.

It is a further object to provide a crane having a jib in two parts movable by a single winding motor.

Further objects and advantages of the present invention will appear from the following description of one embodiment, reference being made to the accompanying drawings in which:

Figure 1 is a side elevation of the crane;

Figure 2 is an enlarged view of the lower part of Figure 1;

Figure 3 is a diagram illustrating the threading of the hoisting and derricking ropes;

Figures 4 to 8 are diagrams illustrating the operation of the crane; and

Fig. 9 is a rear elevational view of the lower portion of the crane.

Essentially the crane comprises a main jib pivoted to a base, an extension pivoted to the head of the main jib, and derricking mechanism controlling both the main jib and the extension and so arranged that in derricking out the extension turns through a greater angle towards the horizontal than does the main jib.

The crane consists of a wheeled chassis 2 on which is mounted a turn-table 4 carrying A-frames 6, a cab 8 and a counterweight 10. The main jib 12 of the crane is pivoted to the frames 6 about an axis 14 and at its upper end carries an extension 16 pivoted to the head of the main jib at 18. A triangular frame 20 forming the heel of the extension is also pivoted at 18 and is joined to the head of the extension by ties 22.

Derricking of the crane is controlled by a rope 24 which is at one end anchored to a shaft 26 carried in brackets 28 on the main jib. This rope passes round a pulley 30 on a shaft 32 carried by the frame 20, then round a guide pulley 34 on the shaft 26 and thence in succession round pulleys 36, 38, 40, 42 and 44 carried by a shaft 46 at the heel of the main jib and by a shaft 48 at the rear of the cab 8. Finally, the rope 24-is wound on a barrel 50 on the shaft 48. When .the rope 24 is wound onto the barrel 50 it tends to raise both the main jib 12 and the extension 16. The weights of the ,main jib and the extension, and the numbers of parts 'of the rope 24 acting on their heels are such that the-main jib is raised in preference to the extension.

tion which in the example is directly in line with the mains stationary while the extension 16 turns towards the horizontal and the crane reaches a position shown in Figure 5. Rotation of the extension relative to the main jib is limited by ties 54 which are pivoted to the frame 20' at 56, and at their lower ends are linked by a cross-bar":

.58 sliding in slots on the main jib 12. After the crossbar 58 has reached the upper end of the slots further unwinding of the rope 24 allows the main jib and ex- ,tension to turn together towards the horizontal until they 'ireach a position shown in Figure 6. It will be seen that the sequence of movements of the main jib and extension is under the single control of the rope 24 and thus only a single barrel and driving motor are necessary to raise and lower both the main jib and the extension.

The ratio of the forces required on the heels of the extension and the main jib to support them varies according to the load which the crane is carrying. To compensate for this, a hoisting rope 62, which is wound on a barrel 64, after passing over a guide pulley 66, is led round a pulley 68 on the shaft 32, a pulley 70 on the shaft 26 and a further pulley 72 on the shaft 32 before passing over a pulley 74 at the head of the extension 16. The tension in the rope 62 thus contributes to the force on the heel of the extension 16 to an extent dependent on the load supported.

The value of the movement of the extension 16 relative to the main jib 12 between the position shown in Figures 4 and 5 is illustrated in Figure l, where the outline 76 represents the near side of a ship having a hatch opening 78. A straight jib which would both clear the rail of the ship and lower a load into the hold would have to be considerably longer than the combined lengths of the extension and main jib of the crane shown. The present crane is not however confined to this use, and provision is made, if desired, for restricting or preventing relative movement of the extension and the main jib 12 by means of a catch 80 which can be swung about the axis 14 so as to obstruct partially or completely movement of the cross-bar 58 in the slot 60. The crane can then move from the position shown in Figure 4 to that shown in Figure 8. This may be of value in clearing overhead obstructions.

The extension 16 is also fitted with a second set of ties 82 pivoted at 56 and joined by a cross-bar 84. This bar 84 usually rests on the ties 54, but if the main jib is lowered below the position shown in Figure 6, the bar 84 engages an upstanding abutment 86 fixed to the frame 6. The effect of this is to stop further rotation of the extension 16 relative to the horizontal so that the lowermost position reached by the crane is that shown in Figure 7 in which the extension has reverted to a position in .line with the main jib. This enables the head of the extension to enter the doors of warehouses and the like.

I claim:

1. In a crane, in combination, a base, a main jib pivoted to said base, an extension pivoted to the head of said main Patented Nov. 1,,1955' Upward movement of the main jib 12 is limited by engagement of its heel with a cross-bar 52. After the jib has engaged .this cross-bar further winding of the rope 24 onto the barrel 50 raises the extension 16 to its uppermost posijib, a tie having one end pivoted to said extension and the other end mounted for limited movement relative to said main jib, and derricking mechanism connected to said main jib and extension to permit pivotal movement of said jib and extension in a derricking-out direction whereby in derriclring out said extension rotates towards the horizontal through an angle greater than that through which the main jib rotates by an amount determined by the extent of said sliding movement.

2. In a crane, in combination, a base, a main jib pivoted to said base, an extension pivoted to the head of said main jib, a tie having one end pivoted to said extension and the other end connected for limiting sliding movement relafive to said main jib, pulleys on said extension, said main jib and said base anda single derricking rope passing round said pulleys and means controlling the movement of said rope to determine the position of both said main jib. and said extension.

3. In a crane, in combination, a base, a main jib pivoted to said base, an extension pivoted to the head of said main jib, a tie having one end pivoted to said extension and the other end connected for limited sliding movement relative to said main jib, means for selectively varying the extent of said sliding movement, and derricking mechanism connected to said main jib and extension to permit pivotal movement of said jib and extension in a derricking-out direction whereby in derricking-out said extension rotates towards. the horizontal through an angle greater than that through which the main jib rotates by an amount determined by the extent of said sliding movement.

4. In a crane, in combination, a base, a main jib pivoted to said base, an extension pivoted to the head of said main jib, slidable means interconnecting said main jib and said extension for limiting relative movement of said extension with respect to said main jib, pulleys on said extension, said main jib and said base and a single derricking rope passing round said pulleys and means controlling the movement of said rope to determine the position of both said main jib and said extension.

References Cited in the file of this patent UNITED STATES PATENTS 970,773 Wylie Sept. 20, 1910 1,920,370 Forsythe et a1. Aug. 1. 19,331 2,031,549 Rufi Feb. 18, 1936 2,524,748 Baker Oct. 10, 1950,

FOREIGN PATENTS 470,295 Great Britain Aug. 12, 1937 955,073 France June 20, 1949

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