How the Koepe hoisting principle works: The Koepe hoisting principle that was mentioned before has the following background: In earlier times the machines had huge cylinders on which the ropes were winded up. This was connected with the disadvantage that - with heavy loads in the pit cages and especially in the inner windings - a great strain was effecting the ropes, because they were winded up very tight. That caused a heavy wear and tear of the rope. That is the reason why a clever man named Koepe had the idea that this effect could be avoided by not winding the rope up, but leading it around a driving wheel and then back to the winding tower and into the shaft.
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Part I of this article Vector, April discussed shaft preparation; headgear superstructure; tail rope protection; underground skip loading; the installation of the lead ropes, and transferring the load to the Koepe wheel. Shortening the ropes It is necessary to shorten the head ropes from time to time due to rope stretch. A simple and effective method was devised to do this: Both skip pans are removed from their respective bridles at bank level.
On the side to be shortened, a specially made pennant is clamped to each rope at a suitable distance above the cappels and a second pennant is clamped to the free end of each rope where it protrudes from the cappels, the bridle being at bank level see Fig.
A two-tonne chain block is attached between each pair of pennants and a slight amount of tension is applied. The hand chains of all four chain blocks are fastened. The bridle, with the chain blocks attached, is driven down and stopped at the lower station elevation m below surface. Two 2,5 cm diameter slings are passed through the bridle crosshead and secured to the steelwork at the station.
The winder wheel is turned slightly to cause the head ropes to hang slackly. The bridle and the short length of tail rope below it is supported by the slings see Fig. The pear-shaped wedge in each cappels is freed and the corresponding free rope end is pulled through to shorten the rope.
The attached chain block is used for this purpose. The bridle is raised to enable the slings supporting it to be removed and the bridle is returned to surface, where the chain blocks and pennants are removed. The free ends of the ropes are cut to suitable lengths and are clamped to the head rope. The pans are then returned to their respective bridles. Using the rope installation equipment, the procedure is as follows: The conveyances are brought to the rope installation positions, one above the loading box, the other about 9 m above the bank in the headgear.
The tail rope is disconnected from the conveyance at the loading box and is lowered to the bottom of the shaft. The new tail rope, wound onto the rope service winder and with a cappels attached, is passed over the sheave wheel and is lowered to the shaft bottom. The auxiliary winch lifts the capped end of the rope to the underside of the conveyance.
The cappels is connected to the bridle. The loop in the tail rope is then adjusted to suit the other ropes and the rope is clamped at the bank by means of a suspension gland type clamp. The rest of the rope is removed from the rope service winder. A rope is now wound on the rope service winder passed over the sheave wheel at the bank and is clamped to the old tail rope, which is pulled up a short distance to enable the connecting pin to be removed from the attachment under the conveyance in the headgear.
The old tail rope is wound onto service winder drum until it is removed from the shaft. The cappels is now attached at the correct distance from the free end of the new tail rope and is connected to the underside of the conveyance in the headgear. Changing a head rope To reduce handling to a minimum and to ensure that the used head rope could be recovered intact so that it can be used as a tail rope if necessary, the following procedure was adopted after much deliberation see Fig.
The winder wheel is driven a short distance to cause the head ropes to hang slack. The head rope to be changed is disconnected from the bridle and the cappels is removed. The opposite conveyance is brought to the bank level. The head rope to be removed is now clamped and suspended from support steelwork D at bank level in the compartment nearest the service winder C. The opposite conveyance is hoisted to release the tension in the rope to be changed.
The rope is disconnected from the bridle in the headgear, passed over the Koepe wheel and lowered to bank level by means of the bank winch A. The new head rope is lowered and the end secured in the cappels, connected to the bridle in place of the head rope just removed. The new head rope is clamped at the bank and the rest of it is removed from the service winder. The end of the rope is passed over the Koepe wheel, the cappels fitted and connected to the conveyance in the headgear.
The old rope is secured to the drum of the service winder and the used rope is removed from the shaft. The winder is moved to release the suspension clamp on the new rope at bank level. The underground bridle is now moved to the station level and the final tensioning of the new rope is carried out. Changing the bridle Both skip pans are removed at bank level and the hinged guides in the headgear of the compartment are opened.
Steel bearers are placed across the compartment to support the suspension-type lamps, the bridle being in the headgear above the bank. All four tail ropes are clamped about 1,8 m below the cappels. The winder drum is rotated slightly to allow the clamps to take the weight of the tail ropes.
Steel bearers are placed across the opposite compartment to support four 50 tonne jacks, the jacking beams and the suspension-type clamps. The head ropes and the bridle are lifted about 30 cm, to provide slack to enable the head ropes.
The auxiliary winch at the bank supports the bridle to allow it to be removed from the compartment. The new bridle is moved into the compartment, the head ropes are attached and then the tail rope connections are put on. The jacks are lowered, the clamps on the ropes are removed and the supporting steel bearers are taken out. The winder drum is rotated to lift the new bridle and tail ropes.
The clamps on the tail rope are removed and the supporting steelwork taken from the compartment. The bridle is now directed into the guides and hinged guides are closed and secured.
The winding system Koepe wheel The winder is designed to haul a payload of 20 tonsnes from a depth of m at a speed of m per minute. The Koepe wheel is 5,8 m diameter. It is manufactured in two halves and is of all welded construction and has a total weight of 70 tonnes. By using a wheel having this diameter it was possible to dispense with deflection sheaves for the head ropes and all their attendant complications. The Koepe wheel is fitted with two brake paths, one on each side of the treads.
The calliper-type brake shoes are actuated by independent brake engines see Fig. Tread trueing device It is essential that the tread grooves on the Koepe wheel be kept to the same diameter. A tread trueing device is incorporated in the design for this purpose and may be used during winding operations.
The device is a pneumatic, rotary, formed cutting tool mounted on a slide rest that allows lateral and longitudinal movement. It is situated below the Koepe wheel and is set with the point of the tool on the centre line of the drum shaft as shown in Fig. Winder bearings The total weight of the head ropes, skips, tail ropes and a single payload is approximately tonnes. The Koepe wheel weighs 70 tonnes, the drum shaft 30 tonnes, and each armature of the two driving motors weighs 25 tonnes.
The total load is carried on two lain self-aligning 76 cm by cm white metal bearings. Each bearing carries about tons. The layout of the winder is shown in Fig 6. Lubrication of the main bearings is by a gravity feed from an overhead tank which can be filled by pumps. Oil rings are also provided to circulate the oil from the reservoirs in the bearing pedestals.
Hydraulic lifting gear Two tonne hydraulic jacks raise and support the drum shaft. They are situated at each end of the drum shaft, between a main bearing and the motor armature as shown in Figs. Steel support columns position the cradle. The baseplate of the assembly is fixed to the baseplate of the main bearing. Brake system Two brake assemblies are on each side of the Koepe wheel.
The brakes are of the calliper type actuated by brake engines which are mechanically independent, but are interconnected hydraulically to operate together. The brake shoes are of the fully floating type pivoted at their centre to the brake posts. The lower pivot for the brake posts is directly beneath the centre of pressure in the brake shoe itself, thereby minimising servo effect and eliminating all tendency to judder or rumble when the brakes are applied fiercely.
The braking force is derived from many helical springs held in compression. The force exerted by the springs is relieved by a hydraulic piston located in the cylinder at the lower end of the brake engine assembly. The braking force applied is therefore inversely proportional to the oil pressure beneath the piston.
Automatic operation solenoid valves for automatic braking. A pushbutton for emergency braking. The helical retarding controller The purpose of this controller is constant control of the rate of retardation irrespective of any variation of load.
This is of importance when the winder is operating under semi-automatic conditions. It has a fixed shaft in the centre on which is a helical thread of rectangular section. There is also an external fixed helical rig with the same pitch as the centre thread. The rig represents the shaft, to a reduced scale. Its peripheral length is approximately 65 feet.
On the rig are mounted several magnet operated relays in suitable positions see Fig. A carriage mounted on rollers and holding a permanent magnet is rotated round the centre thread, guided by two vertical rods driven from the winder drum shaft. As this carriage rotates it follows a spiral path, the pitch of which is the same as the external fixed helical rig.
Accuracy is required in the automatic control of the retardation of the winder. The retardation gear operates through the stepped resistances used in the circuits which regulate the speed of the winder, in this case, the excitation circuit of the Ward Leonard generator. The retardation controller can be used for other signalling, interlocking or control purposes relative to the position of the conveyance in the shaft, such as: Tripping the winder in case of an overrun of the conveyance.
Controlling the change of the mechanical breaking torque or its speed of application. Controlling the rope creep compensation equipment. Preventing restart of the winder in the wrong direction. Operation of the retarding gear In automatic operation, the winder is started by pushbutton and is stopped by the magnetic switches of the helical controller.
The winder accelerates at a rate defined by the setting of the magnetic amplifiers up to full speed Point A. The setting can be adjusted by means of sliding resistances. Full speed is maintained constant to the beginning of the retardation period Point B , irrespective of load.
Koepe Friction Winders
Shakatilar Technical Information Some tons of ore per month could be brought to surface if optimum performance is attained. The men and material winder could only about trips per day, due to the multiple clutching operations needed to serve eight main stations. The rock winder could only average 22 hoisting hours per day at an average of 28 trips per hour, the payload of 11,2 tonnes being drawn from three loading positions in the windeer. The clamps on the tail rope windet removed and the supporting steelwork taken from the compartment.
Samudal Rope sheaves Each set of rope sheaves on the headgear is mounted by means of anti-friction bearings on a stationary axle. The dimensions of sinking equipment had become larger and the total weight of kibbles, ropes and multiple deck sinking stages amounted to about tonne. At present, the average daily hoisting time is 18 hours. Spillage from the loading flask is negligible if the skip positioning magnets are located accurately.
When using a drum hoist the hoisting cable is wound around the drum when the conveyance is lifted. Single-drum hoists can be used in smaller applications, however double-drum hoists easily allow the hoisting of two conveyances in balance i. Advantages[ edit ] Drum hoists require less routine maintenance than a friction hoist, because the haulage cable is fixed to the drum, and therefore have less downtime , and the maintenance regime is less sophisticated. Drum hoists can continue to operate if the shaft bottom gets flooded and less shaft depth is required below the loading pocket, unlike friction hoists where such flooding could cover the tail ropes and so on.
Mine hoist systems