The load part of the inertia consists of the weight of the material to be hoisted, the weight of the cages, cars, and the rope on both drums. If you have multiple cranes or hoists on a common conductor system: Run the 610.14 (E) (2) calculations for each crane or hoist. for those with 24- to 72-in. by 5 ft. face, on which three main gears, between 7 and 8 ft. 5. The fourth column is the same as the third column, except, for the first and last values, which represent torque and not real horsepower in the third column. ENTER THE LENGTH OF THE TRUCK BED (IN FEET) 2. The excitation of the hoist motor and generator, although not constant throughout the cycle, is assumed at an average value of 25 hp. 1, Fig. Stack Overflow for Teams is moving to its own domain! 1. (457 m.) to 2730 ft. per min. This is followed by the various steps necessary to obtain the complete hoisting cycle, which require only calculations of a fairly simple character. The overall efficiency is found to be 40.8 per cent, or a little over 3 per cent, better than when using the fly-wheel set; the difference is largely due to the flywheel and slip regulator loss. Then, for a single-drum, direct-acting engine, Fig. The capacity of the generator will be close to 1000 kw. eg gearbox or pulley loses, motor efficiency etc. After the total inertia of all moving parts is obtained, the moment due to angular acceleration and retardation can be readily calculated by multiplying the total inertia by the angular acceleration and retardation. There is, however, considerable 25-cycle power in use; and in a few instances constant voltage direct current is the only power available for a small or an occasional medium-size hoist. Effect of gearing When a gearbox is fitted between the motor and the drive, it has an effect on the torque, speed and inertia. Wheel Load Design Calculation of Jib, Double Girder, EOT Crane. If the hoist is one that does not drop the weight when stoppe the efficiency is less than 50%. The output of the hoist motor, in horsepower-seconds, is calculated from each part of the cycle and an average efficiency of the hoist motor is assumed at 88 per cent. From this, we can calculate the torque exerted by the mass (a torque which our gearmotor must be able to exceed in order to lift the mass). Where such calculations are seldom made, it is better to use the longer methods; but where the calculations are made daily, short cuts can often be used to great advantage. Substituting the known values in these equations, placing one equal to the other, and solving, we have. Calculation sheet No. Add them together. For this, equations 9 and 10 may be used. A picture depicting the wheel arrangement in the hoist and trolley is shown below with respective mounting on the upper and lower flanges of the I- Beam. inside of the drum surface. Monitoring functions do not interfere with the use of your hoist . P (kW -Shaft) = P (kW . With the d.c. field-control system, the speed of the hoist follows the control lever irrespective of the load and drifting cannot occur; this makes it possible to apply safety devices that would not be effective with an a.c. hoist, also to apply automatic control, which can be made to function without the use of an operator. ; an economic speed for this capacity is 720 r.p.m. This causes the speed to drop and the flywheel to give up energy. Placing these equal to each other, (W + F) D/2 =(P x A x e)L/2. The small cylinders make the first cost lower than that of a direct-acting engine; but the gearing for large hoists is a serious objection. will range from ten to fourteen poles; from 200 to 600 hp., fourteen to sixteen poles; and from 600 hp. Otherwise the load in each leg will vary. Earliest sci-fi film or program where an actor plays themself, How to distinguish it-cleft and extraposition? O = weight of ore in pounds. per ft. From equation 1, K=5000 lbs. If the value of L chosen for trial gives a ratio of stroke to diameter outside of these limits, another value must be taken for L, and another solution made. The high-voltage air-brake magnetic contactor is to be recommended for the primary, especially where frequent operations are necessary. The crane wheel load, usually referred to as maximum wheel load is the total load in pounds that any single crane wheel will see. In general, the drums should be as small in diameter as good rope practice dictates, for the smaller the drum diameter the greater will be the speed, which will permit of a fairly high motor speed or a lower gear reduction. 3,700. with a pull out of 2.4, would be recommended. Fig. At the instant of starting, the power in one cylinder acting on the crank, in the top or bottom position, must have a moment equal to or greater than the moment of the unbalanced load pulling from the circumference of the drum. If the original diameter of the barrel of the reel and the thickness of the rope are properly chosen, the moment of the resistance will be constant. They must be started to a fair speed, in order that the fly-wheel may develop sufficient momentum to carry the crank over the center, before the friction is thrown in to pick up the load. M = mass in Kg. electric european electric hoist bridge crane, europe & german standard for over head crane. in., corresponding to 20 5/8 in. 6 are the same as on calculation sheet No. The maximum length of a drum, aside from question of room, is controlled by the allowable fleet-angle, that is, the acute angle included between two lines drawn from the ends of the drum to the head sheave. Volume = 72 cubic feet. The complete load cycle is plotted in Fig. n (meant to be the greek letter nu) = efficiency losses due to gears/ pulleys, mechanical efficiency (gearbox, wire drum, sheaves) \$\eta\$. In either case the power required during the retardation period is too great to absorb by mechanical brakes. Pump Power P (HP) = q (m3/hr) x (kg/m3) x g (m2/s) x h (m) x p (Pa) / 2685600. Searching for new units, parts or technical knowledge? Most induction motors are designed to have a pull-out torque of twice the full-load torque. ENTER THE LENGTH OF THE OVERHANG (IN INCHES) 3. What you've correctly calculated is the energy needed from the motor (given to the load) each second. In many cases complete equalization is not necessary and considerable saving in flywheel weight and losses can be obtained: by using partial equalization. Double-cylinder engines are used for all the regular work of mining. If L were taken as 36 inches, the area would be 335 sq. t = thickness of rope in inches, The addition of the individual weights is shown on the left-hand margin of sheet No. The inertia of the rotor of this motor, as shown in hoist calculation sheet No. motor. These devices open the power circuit and apply the brakes if the speed is above a predetermined value at any point in the cycle. The same applies to the retardation portion of the cycle, except that when electric braking is used with an a.c. motor all of the power represented by the quadrilateral is drawn from the line and wasted in the rheostat. The present problem will be worked out upon the basis of complete equalization with a slip, of 10 per cent. These values are obtained by adding the variable losses of the hoist motor to the output values in the first column. From the heating standpoint, a 600-hp. The second column gives the input to the hoist motor at the various points in the cycle. Geared:Single Cylindrical Drum. The moment of inertia is the weight multiplied by the radius of the gyration squared and divided by 32. This angle should not exceed 6, in order that the rope may lead well on to the head sheave, and so that one rope will not grind or mount the next one in winding onto the drum. It must also be decided whether the hoisting is to be done in one shift or in all of them. Calculation sheet No. motor would have sufficient capacity as far as heating is concerned, but would probably not have a sufficiently high pull out. The next two columns give the generator constant losses, including exciter losses, which must be supplied by the synchronous motor. Can an autistic person with difficulty making eye contact survive in the workplace? Under such conditions the best solution seems to be the application of a d.c. hoist motor receiving power from either a flywheel or synchronous motor-generator set. Average operating time per day. W= (R + C + O) C = R + O, and is required for the complete calculations of an alternating-current hoist and but two sheets are required for either of the direct-current hoists. up, sixteen to twenty poles. In a mine that is already developed, this is limited by the size of car that can be hoisted out of the mine and that will pass through the underground gangways. After starting, the other cylinder comes in to accelerate the speed, and the two together are able to hoist the load with steam partially cut off and still maintain the full speed. However, since the motor works and stops you may reduce the required power according the duty type-see for instance IEC 60064-1 for duty type. Cable Size Calculation of 125 Kw LT Motor Motor KW = 125 Pf = 0.8, Efficiency = 94% System Voltage, V1 Cable length = 200 m Load Current = P / (1.732 x V x Pf x Eff) > (P = 3 x Vx I Cos = for three phase circuits) = 125000 / (1.732 x 415 x 0.8 x 0.94) ~ 230 A This is the full load current cable needs to cater in Ideal condition. Conical drums, as already noted, are intended to equalize the varying load on the engine, due to the change in length and weight of the rope as the cage ascends and descends. The main gear has about the same diameter as the drum, so as to keep the pressure on the teeth as low as possible; and hence it has a circumferential speed equal to the speed of hoisting. A circuit breaker located in the field circuit can be more readily handled than one in the main circuit. 10. 1 hp = 0.745 kW; Related Mobile Apps from The Engineering ToolBox . O = 5000 lbs. n = number of layers of rope in coil. With a single shaft, the time to raise one load is the time to change or load cars at the bottom, hoist loads, change cars or dump at the top, and lower the empty cars; while, in a double shaft, two cars could be handled while the above programme was being carried out in a single shaft, as the second load would be raised while the first empty was going back down, and changing of cars at the top and bottom would be going on simultaneously. They seldom have governing-devices, their speed being determined by the hoisting-engineer by means of the throttle, the link-motion and the brake. 60 - number of seconds in a minute. stroke. It is recommended that the pull-out of an induction motor be selected at a value 25 to 30 per cent, greater than the maximum value on the load cycle to take care of a possible drop of at least 10 per cent, in line voltage. F = friction in pounds,

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