OTIS Speed Governor Switch TAA177AH1 TAA177AH2

OTIS TAA177AH1 and TAA177AH2 are mechanical limit switches used in compatible elevator speed-governor tensioning and safety-device assemblies.

The switch monitors the position or movement of the mechanical tensioning device. When the mechanism reaches its preset operating position, the switch changes contact state and sends the corresponding signal to the elevator safety circuit.

OTIS spare-parts documentation lists TAA177AH1 as a replaceable switch within a governor tension-device assembly. In the replacement-parts market, TAA177AH1 and TAA177AH2 are also commonly described as speed governor switches, tensioner switches, trip switches, or mechanical limit switches.

This product may also be searched as:

• OTIS TAA177AH1

• OTIS TAA177AH2

• OTIS Speed Governor Switch

• OTIS Governor Tensioner Switch

• OTIS Governor Trip Switch

• OTIS Elevator Limit Switch

• OTIS Safety Device Switch

• Elevator Tension Device Switch

Check the Installation Direction

TAA177AH1 and TAA177AH2 belong to the same general switch family, but they are commonly supplied for different mounting directions.

Public replacement references frequently identify:

• TAA177AH1 as the left-side contact or switch

• TAA177AH2 as the right-side contact or switch

The complete old switch and its mounting position should therefore be checked before ordering. A switch supplied for the opposite side may have a different actuator direction, bracket orientation, or mechanical contact position.

Before quotation, please provide:

• TAA177AH1 or TAA177AH2 marking

• left-side or right-side installation

• complete switch photos

• actuator and lever structure

• mounting-hole spacing

• cable-entry direction

• terminal arrangement

• installed-position photo

• governor or tension-device photo

• quantity required

Confirm the Electrical and Mechanical Details

Market specifications commonly list this switch at approximately 2A and 150VAC. These parameters should still be verified from the original component or elevator documentation before installation.

Besides the electrical rating, buyers should compare:

• contact configuration

• actuator travel

• automatic-reset action

• housing dimensions

• fixing-hole position

• lever or contact direction

• cable gland or wiring entry

• surrounding mechanical clearance

A similar-looking limit switch may not operate correctly if the actuator direction or installation geometry differs from the original.

Replacement may be required when the switch contacts become unstable, the actuator sticks, the housing is damaged, or the governor tensioning mechanism no longer activates the switch consistently.

Before replacing the switch, technicians should also inspect the tensioning mechanism, mounting bracket, operating cam, lever alignment, cable condition, terminals, and safety-circuit wiring. Incorrect mechanical adjustment may cause the same fault even when the switch itself remains functional.

Installation and functional testing should be carried out by qualified elevator technicians. The governor tension-device monitoring circuit and related safety functions must be verified before the elevator returns to service.

For maintenance companies in Saudi Arabia, Jordan, Egypt, Iraq, UAE, Kuwait, Brazil, Colombia, Spain, and Italy, clear photos of the switch, actuator direction, wiring, and complete tension-device installation are recommended before shipment.

FAQ

What is the difference between TAA177AH1 and TAA177AH2?

They are commonly supplied as left-side and right-side versions. TAA177AH1 is generally identified as the left contact, while TAA177AH2 is frequently listed as the right-side switch. The original mounting direction should always be confirmed.

Is this a door limit switch?

Some sellers use a broad “door limit switch” description, but OTIS documentation and multiple elevator-parts references associate TAA177AH1 and TAA177AH2 with the speed-governor tension device. The original installation position provides the most reliable confirmation.

Can AH1 replace AH2 directly?

Not automatically. The actuator direction, mounting side, bracket orientation, terminal layout, and mechanical operating position should be compared first.

What is the common electrical rating?

Replacement references commonly list the switch as approximately 2A at 150VAC. The original switch label and elevator documentation should still be checked before installation.

What photos should I send before quotation?

Please send the complete model marking, front and side views, actuator area, terminal connections, mounting position, and one photo of the complete governor tensioning device.