Designed Twist Lock Manual Override

Designed Twist Lock Manual Override

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Problem:

twist lock manual override showing design for assembly

Fig 1: Twist Lock Override, Designed for Assembly

An important customer needed a manual override for one of our solenoid products. The override was a safety device and had to function reliably even when exposed to adverse weather. The design objectives for the override were:

  • Locking or momentary actuation.
  • Easy actuation with a gloved hand.
  • Low likelihood of accidental actuation.
  • Environmentally sealed construction.

Action:

Rather than borrow the problems of existing designs we took a clean sheet approach. Our solution was to design a rotary manual override which did not experience any internal volume change when actuated. This prevented the device from “breathing ” external contamination that could foul the device and prevent operation. Rotary actuation also provided mechanical advantage to override the solenoid and  prevented accidental actuation if the override was bumped.

The device used a bayonet cam arrangement to convert the rotary action to axial movement and the cam profile provided the locking feature. A widened seal gland provided make up volume for the axial swept volume. The entire device was designed for assemble; part count was kept to a minimum, minimal axes of assemble were needed and no threaded fasteners were used.

Results:                                         

The override met the design objectives and was approved by the customer. This override is now offered as an option on a number of our products.