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43. Tail-end bogie overhauled and reassembled
Note that the gear cover is not in place in this photo.
Transfer of some of the weight of the crane onto a bogie is achieved by turning a square-ended cross-shaft on the bogie by means of a capstan wheel. Mounted on the cross-shaft is a worm-gear which drives a worm-wheel having a threaded bush freely engaging with a threaded portion of a vertical shaft. The worm-wheel bears down via a ball-bearing race onto the upper face of a thrust block bolted to a cross-member of the bogie.
The vertical shaft extends downwards through the thrust block, through a steel ball to which it is affixed, and finally through a lower cross-member. The steel ball locates in a socket in the inward end of cantilever so as to form a ball-joint.
The outward end of the cantilever is connected by two pivot pins to a mounting bolted to the headstock of the crane carriage. As the vertical shaft is taken upwards by turning the cross-shaft, it lifts the cantilever. The cantilever is restrained from tilting by virtue of being connected at three points in a triangular formation, thus as it is raised it transfers some of the weight of the crane into the bogie. To transfer the relieved weight back onto the crane carriage the cross-shaft is turned in the reverse direction.
When the bogie is disconnected from the crane, the cantilever needs to be supported at its outward end in a way which allows a certain level of unrestricted up or down movement so as to ease reconnection. This is brought about by a spring which is situated within a recess in the cantilever and bears upon a cross-member of the bogie. A long bolt passes through the bottom of the cantilever and continues upwards through, in turn, the cross-member, the spring and a spring cap. The effective length of the bolt, and hence the spring, is adjustable by means of a nut and locknut.
The two bogies together relieve this particular crane of about 35% of its weight, reducing the axle-load from 20 tons to less than 13 tons.
ADRR95207 is now Britain's oldest relieving-bogie crane, and is the only remaining example of this early embodiment of the principle (other embodiments are described under Design and Development on this website).
Transfer of some of the weight of the crane onto a bogie is achieved by turning a square-ended cross-shaft on the bogie by means of a capstan wheel. Mounted on the cross-shaft is a worm-gear which drives a worm-wheel having a threaded bush freely engaging with a threaded portion of a vertical shaft. The worm-wheel bears down via a ball-bearing race onto the upper face of a thrust block bolted to a cross-member of the bogie.
The vertical shaft extends downwards through the thrust block, through a steel ball to which it is affixed, and finally through a lower cross-member. The steel ball locates in a socket in the inward end of cantilever so as to form a ball-joint.
The outward end of the cantilever is connected by two pivot pins to a mounting bolted to the headstock of the crane carriage. As the vertical shaft is taken upwards by turning the cross-shaft, it lifts the cantilever. The cantilever is restrained from tilting by virtue of being connected at three points in a triangular formation, thus as it is raised it transfers some of the weight of the crane into the bogie. To transfer the relieved weight back onto the crane carriage the cross-shaft is turned in the reverse direction.
When the bogie is disconnected from the crane, the cantilever needs to be supported at its outward end in a way which allows a certain level of unrestricted up or down movement so as to ease reconnection. This is brought about by a spring which is situated within a recess in the cantilever and bears upon a cross-member of the bogie. A long bolt passes through the bottom of the cantilever and continues upwards through, in turn, the cross-member, the spring and a spring cap. The effective length of the bolt, and hence the spring, is adjustable by means of a nut and locknut.
The two bogies together relieve this particular crane of about 35% of its weight, reducing the axle-load from 20 tons to less than 13 tons.
ADRR95207 is now Britain's oldest relieving-bogie crane, and is the only remaining example of this early embodiment of the principle (other embodiments are described under Design and Development on this website).
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