MAXITORQ ELECTRICALLY ACTUATED CLUTCHES AND BRAKES HOW TO SELECT THE CORRECT CLUTCH OR BRAKE The easiest way is to ask our application engineers. For clutch application, we need to know: Torque or H.P. to be transmitted Speed of the clutch shaft Duty cycle Prime mover (i.e., AC or DC motor, internal combustion engine, etc.) Method of transmitting torque to or from the clutch (sheave, sprocket, etc.) Type of load or mechanism being started This is usually sufficient. However, where acceleration time is important or the duty cycle is grater than 6 per minute we need to know the cycle time, the inertias of the loads being started, and their rotational and/or linear speeds, and the desired starting time. In brake applications, we need to know: H.P. of the drive motor Stopping time desired Duty cycle Speed of the brake shaft Type of load being stopped If the duty cycle is greater than 6 per minute, the thermal energy to be dissipated should be checked against the energy dissipating capacity of the brake. Also, if the stopping speed or accuracy is important, that will influence the choice of the brake size and the control circuit. In both these cases we will need data on the rotational and linear inertias being stopped and their rotational linear speeds, plus the on/off times. The control circuit used is important and we will be glad to assist you in selecting the best control. Tension control applications require special evaluation, since heat dissipation is of major importance and torque is not usually the major factor in choosing the correct clutch or brake. A different type of friction material will also be required, if you want to know more about the calculations and factors to be considered in the selection of a clutch or brake, see the application engineering pages for more data. A REVIEW OF MAXITORQ ARMATURE HUB DESIGNS A feature of the Maxitorq line is the variety of armatures and armature hubs. A clutch coupling connects two in-line shafts, whereas a clutch connects two parallel shafts; therefore, the armature hub designs for these two products are different. The armature hubs used with brakes are the same as those used wit clutch couplings. The following is a brief outline of the standard armature and hub assemblies we offer to meet your requirements and simplify your assembly. Special armature designs are also available, Please call our application engineers if you require more information. For brakes and clutch couplings, we offer three designs: Our flat plate armature is connected to the shaft through a splined hub. It is the lowest cost design and it is widely used. In the anti-backlash design, a flat plate armature is connected to the armature hub by a flat spring. The spring provides zero backlash, fast release and the spline noise is eliminated. For Models 25 and 40 we offer a splined, heavy-duty segmented armature, which provides superior heat dissipation and longer life, and is designed for use in heavy-duty application. An automatic wear follow-up system is optional. In clutch applications, the armature must be connected to a bearing mounted pulley, gear etc., therefore, we offer the following standard designs: Two bearing-mounted hubs, onto which can be mounted the armatures described above. One hub is for use with the splined armatures, and the other is used with the anti-backlash armatures. Self-lubricating sleeve bearings are used. In the 25 and 40 models a keyway is provided on the O.D. of the hub, on which a sprocket or pulley can be counted. In the 12 and 17 models, a knurled hub is supplied. Where customers want to use their own design of bearing-mounted pulley, sprocket, etc., they can use our anti- backlash armature and connect the flat spring directly to their drive component, or they can us a splined hub with a clearance bore and a special connecting flange. RUNNING IN NEW CLUTCHES AND BRAKES With new units the torque can be 30% to 40% below the rated torque until the friction facing and the armature have been run against each other and worn in. This is accomplished by applying about 20% of the rated voltage and slipping the clutch or brake by cycling it on and off for 30 to 40 cycles