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Mechanical Actuators
A Leader in Heat Transfer Components, Products and Systems

Inverted Translating

Ball screw mechanical actuators are perhaps the best solution for load-lifting applications that require high speed and efficiency. C.H. Bull has actuators for every application, offering a selection of Duff Norton ball screw actuators. A Duff Norton inverted translating ball screw actuator will provide the high performance and reliability you need.

Request a quote on an inverted translating ball screw actuator, or contact us to learn more.

Duff Norton Inverted Translating Ball Screw Actuators

Duff Norton’s inverted translating ball screw mechanical actuators are available with lifting capacities from 500 lbs. to 50 tons. They include a number of customizable features, making it easy to find an option that is ideally suited to your unique application (see below).

Ball screw actuators move loads and apply force more efficiently than other types of mechanical actuators, which allows for faster operation—up to six times faster than machine screw actuators—and longer life under load. The ball screw design also reduces friction for lower power use.

Duff Norton ball screw actuators can handle full load in tension or compression. They can be operated with electric, hydraulic, or pneumatic motors. All models are furnished with standard raises in increments of 1”. Multiple units can be synchronized for simultaneous use on the same load.

To accommodate varying application requirements, four different screw end options are available: plain ends, threaded ends, clevis ends, and top plates. Optional limit switches are available to limit the actuator’s vertical travel (up or down).

C.H. Bull also offers upright translatingupright rotating, and inverted rotating ball screw mechanical actuators, as well as Duff Norton machine screw actuators.

Customizable to Meet Your Application Requirements

C.H. Bull can provide a customized ball screw actuator that is tailored to your unique specifications. A number of features can be customized to provide ideal performance for your application. Customizable features include:

•    Lifting capacity
•    Motor type
•    Stroke length
•    Screw end type
•    Limit switch
•    and more

Request a quote on the inverted translating ball screw mechanical actuator you need. Contact C.H. Bull for more information on these or any of our quality products.

Selecting the Right Mechanical Actuator for Your Needs

Step 1: Define operating parameters such as total load, load per actuator (if multiple actuators will be used), lifting speed, total travel required, load type, and ambient working temperature.

Step 2: Determine which type of actuator is best for your application. Several factors should be considered when choosing between a ball screw actuator and a machine screw actuator. Ball screw actuators provide faster and more efficient performance, and require less horsepower to lift an equivalent load. Machine screw actuators are inherently load-holding, and are better suited to applications experiencing constant vibration.

Step 3: Calculate required actuator performance. Select an actuator with a capacity greater than the load you’ll be lifting, then use the formulae below to calculate the performance requirements.

For loads greater than 25% of actuator capacity, consider the torque proportional to the load. 

A) Actuator torque (in.-lbs.) = Actuator load (lbs.) x worm torque at full load

Actuator capacity (lbs.)
(For loads under 25% of actuator capacity, add “Worm torque at no load” to the above formula to account for frictional losses.)

Calculate actuator input RPM (WARNING: Shaft input speed should never exceed 1,800 RPM.)

B) Input RPM = Desired lifting speed (in./min.) x turns of worm for 1” lift
Calculate the actuator’s input HP.

C) Actuator input HP = Actuator torque (in.-lbs.) x RPM

Compare the required input HP to the maximum HP rating of the actuator. If the necessary HP is greater than the specified maximum, select an actuator with a higher HP rating.

If you will be using a gear reducer, multiply the motor HP by the efficiency of the reducer to determine the reducer output/actuator input HP.

For multiple-actuator setups in which two or more mechanical actuators will be shaft driven by one motor or gear reducer, add all the actuators’ input HP requirements. If a mitre gear box will be used, allow for 2% power loss for every 90° turn in the power path.

Step 4: Determine the best actuator configuration for your application. Consider your speed, capacity, and duty cycle requirements when selecting an actuator.

Step 5: If you’re working with a free-rotating or unattached load, the actuator must be configured so that the lifting screw will extend when the actuator is in action. To prevent rotation of the translating screw, Duff Norton provides a square nut inside a square cover pipe for the end of the lifting screw (for ball screw actuators) or a keyed shell and screw (for machine screw actuators). 

Step 6: Verify actuator selection. Be sure to double-check the travel and load requirements of your application, and the ratio, capacity, and speed of the actuator. Determine which end fitting (plain end, clevis end, threaded end, or top plate) best suits your needs.

Safety Warnings

Actuator input speeds should never exceed 1,800 RPM.

Never exceed the static or dynamic capacities of the actuator.

Never exceed the specified horsepower limits of the actuator. If the maximum HP must be exceeded, reduce the lifting speed, select a different actuator ratio, or consider a more efficient or higher-capacity actuator.

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