LiftMaster WS-SENSOR Mechanical Dock-Status Limit Switch

The LiftMaster WS-SENSOR is the mechanical limit-switch accessory identified in the documented dock-management arrangement. The DDO8900W instructions describe a mechanical roller switch used to report trailer-restraint status or dock-leveler position through the approved LMi5 interface setup. Match the exact sensing application and installation instructions rather than confuse this status accessory with the door operator’s internal travel-limit switches. Select the replacement by the complete part number and the installed equipment configuration. A similar photograph or a shared LiftMaster brand name does not establish interchangeability. Confirm the applicable service drawing before ordering so the repair addresses the correct component and its related mounting, connection and operating requirements.

Compatibility — Models, Versions and Exclusions

Identify the Assembly and Plan the Repair

Choose the switch for the actual dock equipment status to be monitored. Verify the mechanical actuation, mounting support and interface requirements before ordering. The same general limit-switch name can refer to very different operating functions; reporting a leveler position does not make this the correct part for a door’s travel-limit mechanism.

Obtain the current sensor and interface instructions before wiring. Do not infer contact ratings, actuator adjustment or environmental suitability from the short catalog description. Qualified personnel should verify both relevant mechanical states and the reported dock status after installation. Preserve required door protection, restraint functions and site loading procedures; a reported status alone does not authorize safe loading.

An electrical symptom does not identify the failed component by itself. Have qualified service personnel inspect the supply, wiring, connections and equipment condition before replacing parts. Record existing labels and terminal references with power safely isolated. A replacement should restore the documented circuit arrangement; it should not be used to change operating voltage, defeat a protective function or compensate for a mechanical load that the equipment cannot safely move.

Specifications and Product Identification

Before Ordering

• Record the complete equipment model, serial information and installed service reference.
• Confirm the current WS-SENSOR recommendation.
• Verify the intended restraint or leveler position arrangement.
• Use the approved interface and sensor wiring requirements.
• Confirm the current supplied inventory and the exact installation and final testing instructions.

Package Contents and Separate Requirements

This offer identifies the mechanical sensor accessory. Confirm current switch, actuator, mounting and connection pieces. An LMi5 interface, restraint, leveler, controller, wiring harness, door safety-sensor pair and complete dock operator are not established as included. Obtain separate application hardware from the approved installation design.

Safety Warnings — Read Before Installation or Service

• WARNING: Electrical service can expose hazardous voltage and moving equipment. Use qualified service personnel and electrical personnel where required.
• Disconnect every applicable mains, battery and auxiliary supply before work. Follow the equipment instructions for stored energy and safe isolation.
• Dock-status indication does not replace restraint, door protection or site loading procedures. Verify both reported states and preserve every required protective function.
• Restore covers and wiring protection, then complete the model-specific functional and safety checks before returning the installation to normal use.

Related Products and Important Differences

• CPS-U monitored photo eyes — separate protection devices for approved commercial-door controls; match the operator and environment.
• TDC12X1BMC MAXUM trolley operator — a complete-operator comparison, not evidence that this legacy service part fits MAXUM.

Frequently Asked Questions

Is it a trailer-presence sensor?

The manufacturer distinguishes WS-SENSOR restraint/leveler-position status from PRE-SENSOR trailer presence.

Does it replace internal door travel limits?

No such replacement is established. It is the documented dock-status accessory.

Is LMi5 included?

No interface is established as included with the switch.

Can status replace dock safety procedures?

No. Preserve the required restraint, door protection and site operating procedures.

Need Help Confirming the Right Product?

Contact Garage-DoorParts.com before ordering. Send the full equipment model, readable part labels and photographs of the installed assembly. Include the dimensions, electrical configuration or accessory details relevant to your project so the listing can be checked against the actual installation.