Implements or apparatus for applying pushing or pulling force – Rack and pinion
Patent
1988-03-31
1989-05-16
Watson, Robert C.
Implements or apparatus for applying pushing or pulling force
Rack and pinion
B66F 712
Patent
active
048303364
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an arrangement in a hoisting device, especially for a derrick comprising two parallel vertical derrick components, each of which carries a rack rail along which the hoisting device can move vertically by means of a respective driving means provided for each derrick component and via toothed wheels engaging the rack rails, the hoisting means comprising a transverse supporting member extending between said two driving means.
In such hoisting devices, the transverse supporting member will be loaded with heavy weights suspended therefrom, for example the weight represented by a drilling string.
If one of the gear transmissions should jam during the lowering of the hoisting device including such large loads, the overall hoisting device including rack rails and the main structure would have a breakdown.
The object of the present invention is therefore to provide a device of the type mentioned in the preamble, which reduces the risk of breakdown upon unbalanced loading, there also being aimed for a system which supervise the various variations of loadings during a drilling operation.
According to the invention the object is achieved in that the transverse supporting member in the area of each driving means comprises a rotatable bearing which at abnormal unbalanced loadings on the two driving means allows a relatively large slanted position on the supporting member, and that the supporting member in the area of one of the driving means also comprises a bracing means which during normal parallel operation of the driving means stiffens the supporting member, but which during abnormal operation is made to collapse to allow a slanted position of the transverse member.
Preferably the bracing means will have a connection to a load measuring device which supervises the loadings on the bracing means, and which when a given load is exceeded actuates the mechanical brakes for the driving means.
If the driving means should still be moving after the engagement of the mechanical brakes, the bracing means would be loaded so heavily that it will break, a fact which involves that the transverse supporting member no longer represents a rigid structure, but an articulated connection allowing for a certain difference in level between the driving means without involving any breakdown of hoisting machinery including rack rails and main structure.
Further features and advantages of the present invention will appear from the patent claims, and will in the following be further discussed in connection with the attached drawings illustrating an embodiment of the present arrangement.
FIG. 1 illustrates perspectively a derrick structure including associated equipment, installed on a platform.
FIG. 2 is a view at a larger scale of an embodiment of the device according to the invention.
In FIG. 1 there is illustrated a derrick structure which is generally designated by reference numeral 1, and which comprises an upper traverse 2 and two parallel derrick components 3 and 4, respectively, which together with the traverse 2 define a space 5 for accomodating a vertically movable hoisting device 6, which is further illustated in FIG. 2.
The hydraulic hoisting device 6 comprises for example four hydraulic motors 7, each of which via a transmission gear 8 drives its own gear wheel 9, which in turn is in engagement with rack rails 10 mounted along the derrick components 3 and 4, respectively.
The braking of the hydraulic hoisting device 6 takes place by means of for example mechanical brakes, which are adapted to be activated automatically if the hydraulic pressure should disappear. The shafts of the gear wheels 8 and 9 can be supported in ball bearings and work preferably in a closed oil bath.
In FIG. 2 there are also illustrated guiding wheels 11 cooperating with the rack rails 10 for horizontal guidance of the hoisting device 6.
FIG. 1 also illustrates a control desk 14 provided in a control room 22, as well as a drilling string 15 which at its upper end is conneted to a drilling machine 18, and which at the other e
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Gans Bernard R.
Watson Robert C.
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