Ball Screws Give the FLASH 36 Its Strength
The construction of a new, highly automated FLASH 36 spring tester for a major U.S. transit authority gives us the opportunity to give you a rare look at the internal workings of a Larson Systems motorized spring tester. One of the most prominent features is the ball screws and drive system.
Ball screws are used in aircraft and missile systems to move control surfaces. In cars, they translate the rotary motion of the steering wheel into linear (axial) motion to the steering column. Perhaps the largest use for ball screws is in machine tools - for positioning and moving the bed and spindle.
The FLASH 36 has four, 2-inch-diameter ball screws, one in each corner of the machine. Their primary purpose is to keep the testing platforms parallel and rigid when you’re applying a load to a spring. They are made to close tolerances - ideal for high-precision positioning. The nuts that secure the ball screws to the platforms are "pre-loaded" to remove clearance and initial load deflection.
We take it a step further here at Larson Systems and pre-tension the ball screws. Each one is stretched as it is installed to give the spring tester a greater level of rigidity.
The four ball screws give the FLASH 36 tester exceptional parallelism. With a single ball screw, force applied to a spring may cause the upper platform to become cocked at an angle, throwing your measurements off. Single ball screws work well for testing springs with lighter loads, and you'll find them in many Larson spring testers. Two ball screws provide more side-to-side stability. But for testing big springs like those on railroad passenger cars, you need more. To handle a 10,000-lb. load while maintaining parallelism and minimizing deflection, you need four ball screws. Not only do they help the platforms stay level from side to side, they keep the platforms parallel to each other from front to back.
To protect the ball screws from contamination by dirt and other abrasive particles, they are covered with telescoping spring steel made in the U.S. Some of you test in very dirty environments, so this protection is an absolute must! The screws are connected by a heavy-duty timing belt that assures synchronization from the large servo motor drive.
Larson Systems Inc. has built its reputation for legendary accuracy through innovative engineering and top-quality materials. That’s the reason so many 30-year-old Larson testers are still hard at work today.
Would you like to learn more about this latest and most advanced iteration of our FLASH 36? Contact Bruce Hill at 763-780-2131, ext. 106 or email him at firstname.lastname@example.org.