GB602204A - Improvements in cranes - Google Patents

Abstract

602,204. Cranes. FAURE, A., and FAURE, A. Oct. 26, 1945, No. 28353. Convention date, Sept. 24, 1941. [Class 78 (iv)] In a crane of the kind comprising a horizontal jib pivotally mounted at the top of a mast and forming a runway for a lifting trolley, and in which a counterbalancing jib is provided, lack of balance between the jibs when an attempt is made to lift a load exceeding a prescribed limit consistent with the location of the trolley, is caused to stop the lift or travel of the load through the differential action of the jibs on a member controlling the engagement between the prime mover and the particular transmission mechanism by which the load is being shifted. As shown, the jib 2 forming the runway for the trolley 13 is pivotally mounted at 2<1> on a mast head 3 and is counterbalanced by a weighted jib 6 pivoted at 6<1> on the mast head. The jibs are connected by rods 8, 9 to an arm of a lever 10 pivoted at 11 to the mast head, the other arm of this lever being forked and engaging a tripping shaft 12. The trolley is operated by a cable 14 passing round pulleys 15 and over a drum 16 which is driven through a bevel gear 17 by a sleeve 18 loosely surrounding the shaft 12 and driven through a spur gear 19 by a shaft 20. This shaft extends down through the mast 21 to a transmission gear 22 operated by a control rod 24 fitted with a handle 24<1>. The load hoisting cable 25 is anchored to the jib 2 at 26 and passes over a pulley 28 down the mast to a winch 29 provided' with a clutch 30 operated by a control rod 32 provided with a handle 321. The mast head 3 is rotated on rollers 5 by a pinion 35 engaging a toothed ring 34 on the head, the pinion being secured to a shaft 36 connected with a reversing gear 37 controlled through a rod 39 by a handle 39<1>. The winch 29 and gears 22, 37 are driven from an electric motor 41. The handles 24', 32<1>, 39<1> may be clamped at any position along their respective rods. When an attempt is made to lift an excessive load, the jib 2 tilts slightly and through the tie-rod 8 rocks the lever 10 clockwise so as to depress the shaft 12 which through a fork 43 operates a linkage 42 connected to the control rod 32 so as to operate the clutch 30 and stop the winch. Similarly, when a load is being carried by the cable 25 and an attempt is made to move it beyond its safe radius, the jib is again tilted and through the shaft 12 and linkage 42, the rod 24 is operated to de-clutch the gear 22 and bring the trolley to rest.