Classification and Comparative Assessment of Drum Rearrangement Mechanisms in Mine Hoisting Machines
Abstract Generated abstract
This paper classifies drum rearrangement mechanisms used in mine hoisting machines for rope length regulation and related operations, using design and operational criteria such as disengaging device, locking device, drive type, adjustment increment, dynamic loading, and degree of automation. It compares bolted, wedged gear, cam and toothed clutch, friction clutch, and worm mechanisms in terms of reliability, labor intensity, ease of control, adjustment precision, impact loading, and operational safety. The assessment recommends cam or toothed clutches for large hoisting machines because of their reliable shaft connection, and suggests worm mechanisms for small machines provided a simple remote mechanical drive is developed. It also argues for separate drum brakes, limited auxiliary use of locking rods, and greater automation or semiautomation, including rope slack monitoring, in hoisting installations.
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PROCEEDINGS
OF THE TOMSK ORDER OF THE RED BANNER OF LABOR
POLYTECHNIC INSTITUTE named after S. M. KIROV
Vol. 103
1959
CLASSIFICATION AND COMPARATIVE EVALUATION OF MECHANISMS FOR SHIFTING THE DRUMS OF MINE HOISTING MACHINES
N. I. KLYKOV
Mechanisms for shifting mine hoisting machines are used to regulate the length of the rope and for other operational procedures.
It is proposed to classify mechanisms for shifting drums according to the following design and operational features:
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By type of disengaging device: a) connecting bolts or pins; b) gear wheels with wedging segments; c) cam and toothed clutches; d) friction clutches; e) worm shifting mechanisms.
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By type of locking device: a) retaining rod; b) load block brake with manual engagement; c) locking device with remote control.
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By type of drive: a) manual; b) mechanical drive.
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By increment of rope-length adjustment: a) with stepwise adjustment; b) shifting mechanisms with stepless adjustment.
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By the nature of application of the dynamic load: a) with impact; b) with non-impact application of the acting forces.
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By degree of automation: a) non-automated; b) with semiautomatic action; c) automatically operating shifting mechanisms.
The use of connecting bolts or pins provides reliable coupling of the loose drum or bobbin with the shaft, but in this case the operations of coupling and disengaging the drums are exceptionally labor-intensive.
Shifting mechanisms with gear wheels and wedging segments do not eliminate manual labor, but coupling and disengaging of the drums take place more quickly than with a bolted connection. Owing to the presence of clearances between the teeth, the elements of the disengaging device are subjected to impact application of loads. The use of locking rods, especially those located in the basement room, is extremely inconvenient for maintenance personnel.
The most widespread have been shifting mechanisms made as a cam or toothed clutch. Their principal advantages are reliable coupling of the loose drum with the machine shaft and remote control of the disengaging device.
Operations for coupling and uncoupling the drums are performed easily and quickly. At the same time, however, the stepwise nature of regulating the rope length is not eliminated, and impacts occur in the elements of the uncoupling device.
The main advantages of drum-shifting mechanisms made in the form of a friction clutch over the preceding types are: a) the possibility of fixing the drums of the hoisting machine in any position relative to one another; b) protection of the elements of the uncoupling device, as well as of the mechanical part of the machine as a whole, from sharp impacts and jolts. However, under dynamic application of loads, slipping of the drums occurs, which is undesirable in view of the resulting discrepancy between the readings of the depth indicator and the actual position of the hoisting vessels in the mine shaft. Therefore these mechanisms for shifting drums cannot be considered fully reliable in operation.
The worm shifting mechanism designed by Giprouglemash combines the reliability and simplicity of toothed uncoupling devices with the precision of rope-length regulation characteristic of friction-type shifting mechanisms. The disadvantage of this design is the absence of a mechanical drive with remote control.
The loose drum is most reliably connected to the shaft of the hoisting machine by wedging with the aid of a cam or toothed clutch; therefore we recommend them for large hoisting machines.
On small hoisting machines, along with toothed and cam clutches, worm shifting mechanisms should be used; for these it is necessary to develop a simple and reliable drive with remote control.
As a locking device, it is advisable to use a separate brake for the left and right drums. For small hoisting machines, a separate brake for the shifting mechanism with remote control may also be recommended. The use of locking rods is rational as an auxiliary means of securing the drums in the event of a prolonged stoppage of the hoisting machine, brake repairs, etc.
On automated hoisting installations, provision should be made for automatic operation of the drum-shifting mechanism during regulation of the rope length or when changing over to operation from another level. For non-automated hoisting installations, schemes should be developed for semiautomatic operation of the shifting mechanisms and methods for automatic monitoring of rope slack with the delivery of the corresponding signals to the hoist operator.