Motors & Linear Actuators

Motor Wiring and Performance
　　1. Gear trains simply take input speed and torque and multiply or divide them depending on ratio. Some torque is lost due to friction, but the basic output performance mimics the input performance. just scaled up or down for ratio. Therefore the motor performance characteristics you see on this page will be the same characteristics you would see from a gearmotor.
　　2. Shaded pole motors run on AC voltage and only rotate in one direction. Standard models have only two lead wires and can be turned on and off by putting voltage across the two wires. Performance characteristics are similar to PSC Wiring (1).Performance (1).
　　3. PSC (permanent split capacitor motors) run on AC voltage and are reversible. The capacitor must be in the circuit at all times for the unit to run properly. Standard models have three or five lead wires and should be hooked up as shown in Wiring(2a) or (2b) Performance(1).
　　4. PMDC (permanent magnet DC) motors run on DC or rectified AC voltage and are reversible. The more closely the input voltage resembles pure DC, the more efficiently the motor runs(less heat rise, longer brush life).These motors have two lead wires and the direction of rotation is determined by the polarity or the input voltage. Wiring (6). Performance (4).
　
Thrust Rating vs. Duty Cycle
　　All of our linear actuators are intermittent duty rated. The thrust rating shown in the Data sheets are set up around 20% on-time per minute of operation. For infrequent bursts of power, most units can handle up to 1.25 times rated load. Consistent heavy cycling of loads in excess of the rating may cause units to fail. When in the design stage, keep in mind that although Adacel linear actuators are designed to provide equal thrust in both directions, the load bearing capacity is higher in compression than in tension.
　　As with the gearmotors before, the performance linear actuators mimic the performance of the motors that drive them. The only difference is that rotary speed and torque are replaced by linear speed and thrust. However, start thrust breakdown thrust and pull-up thrust all exist just as would be expected.
　

Mounting and Alignment

　　In order to get proper performance and maximum life, linear actuators should be mounted to be free of side loads. The best way to ensure this is to use clevis mounting at each end and to ensure that the clevis mounting pins remain parallel at all times.
　　Also, be sure that the pins are evenly supported on each side and the load is centered about the actuator. The last consideration in mounting is restraining torque. All linear actuators have rotating output shafts and the travel tube or acme shaft will simply rotate as well unless it is kept from rotating. The restraining torque requirement can be calculated as;　Restraining Torque (lb-inches)=2*Axial load(lbs)
　

Linear Actuator Wiring

　　AC linear actuators come standard with PSC motors that have capacitors already mounted and wired in. DC linear actuators have two wiring diagrams depending on the amp draw of the motor. All units are prewired through limit switches that shut the actuator off at either end of stroke. (Wiring 7a,7b,7c) 　

Torque Ratings vs. Duty Cycle

　　 All gearmotors have duty cycle specified on individual units. For those that are rated continuous, the motor, bearings, gears and shafts are designed to run continuously at the listed torque value without overheating. Lower torque amounts can extend life or specifying a particular life can help you. Torque levels higher than specified are sometimes possible on an intermittent basis, at times up to 1.5 times rated load. If, however, these loads will be frequent, premature failure may occur, Again ,Adacel can help you specify your needs. For most models rated as intermittent, the motor and power train can operate for sustained periods (up to several hours)at rated torque values, but when run continuously the motor can deteriorate rapidly. Used typically in cycling operations, where the duty cycle preludes mechanical overheating, these units can provide many years of reliable service.
　　For intermittent applications, many times a smaller, more cost effective motor or gearbox can be used. Be sure to specify duty cycle completely on application data sheets so that the optimum gearmotor can be selected.
　

Torque Overhung Load

　　
　　All gearmotors have torque and overhung load specified on individual data sheets.
　　Torque is the tendency of your load to twist the output shaft of a gearmotor. Torque is measured as a force x a distance. For example a (2) lbs, weight supported (12) inches away from the centerline of the output shaft of a gearmotor would require 2 lbs.*12 in=24 lb-ins of torque to move.
　　Knowing your exact torque requirements helps you optimize your gearmotor selection. You can get just the gearmotor you need, or if you want some safely margin, you¨ll know how much safety margin you've got. Torque can be measured using a torque wrench or using a wheel of a known diameter and force scale (similar to a postage or fish scale).Torque can also be calculated based on load and its vectoral distance from the gearmotor output shaft.
　　Your torque load is made up of a force at a distance and that force constitutes an overhung load. If the gearmotor/shaft couples to a shaft that is supported at each end, then you have isolated the overhung load from the gearmotor. In this case, be sure that the coupling arrangement allows for proper alignment between the gearmotor shaft and the supported shaft. If it doesn¨t, it can preload the bearings in the gearmotor and cause performance and premature failure.
　　If the gearmotor output shaft transmits its torque through a chain, pulley, gear train or rack and pinion, these devices will create an overhung load on the shaft. This load can be figured by the equation below.
　　K is a load factor for the type of transmission you use. For chain and sprocket. K=1.0;for belt and pulley. K=1.5. Be sure that your pulley. Sprocket or pinion diameter is large enough to stay within the published overhung load capacities.