Allspeeds Limited have been manufacturing variators for many years and have played a large part in industryÕs ever-growing awareness of the positive advantages to be obtained from controlled variable speed drives. Modern technology demands the ability to change speeds frequently, whether by manual methods or automatic control systems. The Allspeeds Variator is ideally suited to these requirements, as the control mechanism is light, positive and extremely accurate. Predetermined speeds can be quickly selected and accurately maintained. Furthermore, the variator is the mechanical drive of simple design and capable of being serviced by any competent fitter. This is an important consideration for manufacturers who sell to international markets. Allspeeds Variators offer speed ranges from 11:1 variation and input powers 0.18kW to 75kW. From the simplest application utilising a straightforward free shaft ball variator to the sophisticated cone type K series unit incorporating closed loop control servo systems, our applications engineers are available to help with your specific drive problems. Ball Series click to see larger image Input Power Ratings Input power ratings of variators at various input speeds between 500 rev./min and 1410 rev./min. Applications where input speeds below 500 rev./min. or above 1800 rev./min. should be discussed with our Engineering Department. Output Speed Ranges with free shaft ends From one-third of input speed to three times input speed (a stepless speed variation of 9:1) With flange mounted motors and reduction gears * These reduction gears have CONTRA-ROTATING input and output shafts. To obtain output speed ranges other than those listed, non-standard reduction gears can be supplied. The output speed ranges shown are only approximate, since motor speeds vary with power ratings. Standard motors are suitable for all normal 3-phase 50 Hz supplies. Motors for special voltages, flameproof conditions, single-phase supplies, etc.., are available on request. It will be noted that when high input speeds are used such as 1410 rev./min., the output speed range of the unit when fitted to a reduction gear is reduced to 6:1. This is due to the input speed limitation of the reduction gears. Where the electrical supply is 60 Hz, all output speeds are increased by 20%. Variator Efficiency Fig. 1 shows a typical variator efficiency curve related to output speed. It will be seen that the variator has a very high efficiency at output speeds between half and double the input speed, ie., for the majority of the output speed range. The curve is representative of a horizontal unit - efficiencies varying slightly with different sizes of variators. Individual efficiency curves are available on request. Vertical units incorporate an internal lubricating pump which, of necessity, reduces the efficiency of the variator. Efficiency curves for vertical units can be supplied if required. Fig. 1 Speed holding Under constant load conditions the speed-holding characteristic of the Kopp variator is inherently stable. Under varying load conditions however, speed fluctuations can occur. Fig. 2 shows percentage speed deviation under varying load with a constant input speed of 1500 rev./min. It must be emphasised that the speed deviation referred to above is not due to slip, but to variations in load producing corresponding changes in axial pressure. Due to the elasticity of the component parts to which this pressure is applied and to a lesser degree to the elimination of running clearances, any change in the load will result in minor alterations in the relative positions of the drive balls and drive cones, and will cause a slight change in the speed ratio. For example, where input speed and output speed are both 1500 rev./min. it will be found that the speed deviation from full load to half load is only 0.7 per cent. It should be borne in mind, however, that under CONSTANT LOAD conditions the deviation of speed may be as little as 0.1 per cent. In practice, when speed fluctuates with load, it can most frequently be attributed to a pull-down of the speed of the prime mover. Fig. 2 Constant Speed Operation Due to the elasto-hydrodynamic film which exists between the drive surfaces, prolonged running at a set speed will not affect the life of the unit, nor will it impair the sensitivity of the speed control. Speed Regulation The output speed of the variator is controlled by a worm shaft which requires twenty turns to give the full 9:1 speed range. Fig. 3 shows changes of speed relative to turns for the control worm shaft for all sizes of variators. These result in an almost linear graph, deviation being no more than 5%. To obtain this linear relationship, it is essential that the drive shaft nearer the control is used as the input shaft. Fig. 3 Output Torque Ratings Apart from varying efficiencies shown in Fig. 1, the output power of the variator throughout its speed range follows constant power characteristics. As will be seen from Fig. 4, this results in high torque capacities at low speeds, and low torque at high speeds. Where a unit is applied to constant torque requirements it is essential that, in selecting the size of the unit, it should be capable of providing this torque at the highest required speed. Fig. 4 At input speeds below 1500rpm multiply output torque by the following factors: Ball Series Dimensions Type F, H and M Click to enlarge Click to enlarge *166mm if motorised All dimensions are in millimetres Certified drawings on request Type FR, HR and MR Click to enlarge ONLY USE FOR INFORMATION PURPOSES (Request certified drawing) Back to Top