Each day engineers at Joyce/Dayton provide solutions for complex industrial systems. This educational video offers an inside look at the anatomy of a 4-jack synchronized system which was designed to control an optical table.

The design for this system began when Joyce Application Engineers received a customer request with the following specifications:

  • Four jacks were needed to lift and position an optical table over a range of 48 inches.
  • Each jack needed to move 2000 pounds at a travel speed of 5-10 inches per minute.
  • Each needed to be independently motorized and synchronized to within +/-0.3 inches of the other jacks.
  • Electrical power available at the site was to be three phase, 230 volt, 60 hz. Handwheels were needed as backups in the event of power outage.
  • The control system needed to run automatically and include ten programmable positions.
  • All system components needed to be compatible with customer’s clean room requirements.

Because the jacks were to be part of a synchronized system, the application engineer worked closely with the electrical engineer to recommended the correct inverter duty motors. He also specified a travel speed that was compatible with the capabilities of the PLC.

Synchronized controls, shown here, enable the system to operate smoothly, keeping all jacks within a prescribed tolerance of +/-0.3 inches.

Equipment for the system was housed in two enclosure cabinets.

The HMI/PLC cabinet includes a touch screen or Human Machine Interface and Programmable Logic Controller. The operator is able to control the motor operation by using the HMI screen.

The VFD cabinet houses the Variable Frequency Drives that control the motors’ speed and direction. This cabinet includes 4 VFD’s, one for each motor. The VFD allows each motor to operate at varying frequencies from zero to 60 hertz enabling speeds to be increased or decreased as needed to maintain synchronized movement of all jacks in the system.

In this case, specifications for smooth operation required that the jacks be synchronized to within +/- 0.3 inches during travel. The logic of the control system was designed to constantly compare the relative position of the jacks and then make adjustments to motor speeds to keep all units synchronized. A successful system design required both the mechanical design and the electrical design to be compatible. This is an area of the design that required cooperation between the application and electrical engineers because the operating speed of the jacks had to allow the processor time to react and change motor speeds to maintain synchronous operation. The finished design met all system requirements and was quite simple to program and operate.