CEF Industries was one of the first companies to introduce electro-mechanical aerospace qualified actuators.  We can offer our customers the finest quality actuators with high reliability and the flight heritage to rely upon.  Over the years we have designed literally thousands of different electro-mechanical actuator configurations.

When designing an actuator, we use readily available aerospace quality motors, both brushed and brushless, from a variety of manufacturers or manufactured in-house.  This allows us to match the right motor with the right applications.  If needed, CEF can custom design & manufacture motors built to meet the requirements.  We next combine our motors with our robust geartrains and if needed position transducers to produce a highly reliable weight optimized actuator.  As part of the design CEF also incorporates electronics and filtering to meet the specified environmental requirements.

CEF offers both custom designed linear and rotary actuators and a standard actuator product line of linear actuators referred to as Model 20 actuators.  For our custom designed actuators we can custom tailor an actuator to meet your performance, life, reliability and size requirements.  Submit a Custom Quote Request defining your requirements and once we have a copy of your requirements we will contact you to move the process forward and provide you with an outline drawing optimizing a solution for your review.

CEF has vast experience in a number of Aerospace and Defense applications for actuation.  Our most common actuators are well suited for applications such as:

• APU Inlet Door
• RAM Air Door
• Utility Door
• Landing Gear Uplock
• Aircraft Trim
• Air Bypass Doors
• Seat Adjustment 
• Canopy Actuation
• Engine Control
• Valve Control

Whether a custom designed actuator or a Model 20 actuator is used, please remember that CEF uses stringent quality control checks, computer aided design, FEA and the highest quality components in building our actuators.  Most of the actuators we supply require minimal maintenance over their installed life.  

Model 20 Actuator Operational Description 

If your requirements are more flexible or if you have limited time or funding for custom development, perhaps our standard Model 20 Linear Actuators will suit you better. These Model 20 actuators are rugged RTCA-DO 160E qualified and are typically used with strokes up to 5 inches, limit switches or hall effect sensors at end of travel, and load less than 250 lbs. We also have a variety of speeds, mounting options, electrical connecting options, electrical protection options, and annunciation options, please see the online catalog below for standard Model 20 actuator options.

Basic Elements of Construction:

The Model 20 converts the torque and speed of an electric motor to linear motion. Four main components are involved:

Model 20 Electric Motor

The Model 20 actuators are built with a commercial-off-the-shelf, 28VDC, permanent magnet, fractional horsepower motor. This motor was chosen for its optimal performance and cost over the envelope specified. Motor speed and therefore rate of linear movement will vary as a function of voltage (and load). All Model 20 actuator performance charts are based upon 28VDC input.

Model 20 Gear Set & Screw

Motor rotational torque and speed are converted to linear force and speed using a gear reduction set and acme screw. For a given voltage, Model 20 actuator output shaft linear speed and operating load carrying capability will be determined by the gear set ratio, screw lead and their mechanical efficiencies. By selecting different combinations, a range of standard performance curves can be generated. The performance envelope shown for each of the Model 20 actuators below was bound by maximum motor efficiency and specific application constraints such as limit loads on the output shaft.

Model 20 Power and Control

Application of 28VDC to pin A relative to common (pin C) will initiate actuator extension. Upon full extension, power to the motor is internally cut off, stopping motion. Removal of 28VDC from pin A and applying it to pin B will cause retraction. Annunciation is available in two options. Select the desired interface and corresponding connector as indicated in the online catalog below. 

Model 20 Speed/Operating Load

Actuator output shaft speed and load carrying capability are inversely related. For a given voltage, motor, gear/screw reduction set and system mechanical efficiencies, an actuator’s output speed/load performance can be plotted. Due to variation in mechanical efficiencies from one actuator to another, the performance is really a series of curves resulting in an envelope of capability. The Model 20 uses six (6) spur gear and acme screw combinations: three (3) single and three (3) double-lead screws. Model 20 actuators using single lead screws will not back drive.  While double lead screws provide increased speed of linear movement they are susceptible to back drive/creep. If back drive/creep is not desired, consult CEF Applications Engineering for alternative approaches. 

Model 20 Load

Operating load is the load at which the actuator is normally expected to operate and the design load upon which the life and speed requirements of the actuator are generally based. Structural load limit is the applied load which the actuator will withstand without failure or permanent deformation of a structural member.

Model 20 Back Drive/Creep

Back drive/creep is the ability of an actuator to be reversed by a load applied to its output end. Generally, the more efficient the gearing/screw combination, the more susceptible that combination is to back drive/creep. While double lead screws are commonly used to provide increased speed of linear movement, they are more susceptible to back drive/creep. If back drive/creep is not desirable, select a single lead screw or consult CEF Applications Engineering.

Model 20 Braking

Braking can be applied to ensure more accurate positioning, load holding and overall repeatability. The Model 20 utilizes dynamic braking which removes kinetic energy from the system by shorting the motor. For applications where more accurate extend and retract position limits are required, consult CEF Applications Engineering.

Model 20 Stroke

Electrical stroke is the working stroke and is determined by limit switch settings. The Model 20 uses Hall sensors as limit switches at either end of the stroke for extend and retract control. Hall sensors are used for their high accuracy and reliability. Electrical stroke is individually calibrated and tested for each unit at the extend and retract positions to within ±0.030 inches for an overall stroke accuracy of ±0.060 inches. Mechanical stroke is the travel determined by the actuator’s mechanical stops which are employed as back-up to the electrical stops. Model 20 mechanical stops are typically positioned 0.090 inches beyond each of the electrical switch positions. The Model 20 offer electrical stroke ranges from 0.59 inches to 5.00 inches in 0.01 increments.

Model 20 Repeatability

Repeatability is the ability of the actuator to stop at the same point in its travel each time when de-energized by its limit switches. Model 20 repeatability at no-load is typically 0.005 inches.

Model 20 Current Draw

Current draw will be a function of mechanical load and the particular gear reduction set chosen to drive it. 

Model 20 Duty Cycle 

Actuator life will be a function of duty cycle, power input, operating temperature and load conditions. The Model 20 were designed to provide optimal life at a 25% duty cycle, 0.6 amps and 72°F, with a maximum continuous operation less than sixty seconds. For the effects on life in applications beyond this, contact CEF Applications Engineering.

Model 20 Mount and Output Shaft Fittings

The Model 20 offers optional mounting and output shaft fittings.

Model 20 End Play

End play is limited to 0.010 inches maximum under a 10 pound reversing load.