UPGRADING A 1960’S SHELL 4-BALL TESTER TO VARIABLE SPEED
4 Ball Machines test grease under extreme pressure up to and beyond the point of failure. Tests include ASTM D-2596 for weld point and ASTM D-2266 for wear rate.
A grease manufacturer in the NW of England needed to carry out Weld Point and Wear Scar tests at a variety of RPM’s, rather than just at the industry-standard 1,500RPM.
This could be achieved by either buying a new 4-Ball Tester or modifying the original machine. The machine was mechanically in good condition but the electrical system had deteriorated significantly.
Our solution was to:
- Replace the single phase drive motor with a 1.5KW three phase unit
- Add a variable speed inverter to drive the motor and program it to respond in a similar way to the original motor
- Install a tachometer on the motor shaft to read and display the RPM
- Add a simple controller and data exporter that would shut off power at the weld point and also transmit RPM vs shaft revolutions via USB to a computer
The result was a 4 Ball tester with two additional capabilities. One was the variable speed and the other was the data acquisition capability