Engineers and designers frequently use screw jacks in the design of lifting and positioning equipment. They know that mechanical jacks offer reliable lifting and holding options that can be easily incorporated into their systems.
Once loads, duty cycles, and travel speeds are established, designers must choose the type of jack to select – Ball screw jack or Machine screw jack. Both are good choices for reliably lifting and positioning loads, but when should designers choose machine screw jacks and when should they choose ball screw jacks? Consider the inherent traits of each type of jack.
MACHINE SCREW JACKS
- They are best for slower movement and low to moderate duty cycles.
- Most machine screw jacks are inherently self-locking in the absence of vibration.
- Machine screws are typically 30%-40% efficient.
- A brake motor is usually NOT required to hold position on self-locking jacks.
- Stainless steel, metric, and motorized jack models are available with machine screws.
- Anti-backlash devices can be specified to limit backlash in reversing loads.
BALL SCREW JACKS
- Are capable of moderate to high duty cycles.
- Move loads faster and with less horsepower.
- They are NOT self-locking and require a brake motor to hold position.
- Ball screws are typically 90% efficient.
- They are NOT suited for manual operation.
- Ball nut life can be reasonably calculated.
- Are good for moving loads with longer continuous travel.
AS A GENERAL RULE
Choose a Machine screw jack if you have a low to moderate duty cycle, slow travel speed (up to about 21 inches per minute), and require a self-locking screw.
Machine screw jacks are versatile, dependable, and are used in countless applications. They are frequently used in steel machinery, packaging machinery, food processing machinery, and in wash down applications.
Choose a Ball screw jack if you have a higher duty cycle, faster travel speed (up to about 55 inches per minute), and do not require a self-locking screw.
Ball screw jacks are versatile, accurate and dependable. They are used in many of the same industries as machine screw jacks. Ball screw jacks should be chosen over machine screw jacks when faster speeds and higher duty cycles are required or for quick, repetitive operations on presses and on cycling equipment where a calculated ball nut life is required.