Failure to activate Over-speed governor

• Description of defect

Tension spring that permanently deformed will cause failure to activate safety gears which supposed to stop the lift from falling. Permanent spring deformation is the result when the internal stress exceeding the yield point of the material, which can be occurred during design, operation, or maintenance stage. As the gap between the coils gets visibly reduced, it is a sign that the spring in under compression and the worst condition is when the spring may be solidly closed

• Causes

1. Failure to engage the pawl and the ratchet wheel, due to improper connection of deformed tension spring

Deformed spring end of overspeed governor resulting in poor connection on pawl [16]

2. Pin (pivot joint) of the pawl is rusted;

Rusted pin will increase the friction of the pin, thus damaging a quick response of the overspeed governor’s pawl, and finally resulting in failure to activate safety gears

Rusted pin of the pawl of goverspeed governor [16]

• Diagnostic/testing method

The safety code of overspeed governor construction and installation shall be refereed to EN 81-1 code. The type of examination for overspeed governor shall be referred to EN 81-50, where a minimum of 2 tests shall be conducted with acceleration 0,9 – 1,0 gn to check the strength of overspeed governor.

• Good practices

The electrical and mechanical tripping speeds shall be in accordance with the requirements of SS550 code.

• Corrections

It is very crucial to ensure that the overspeed governor able to work properly as it will act as the safety device which activate the safety gear, in the event where the elevator car exceed the travel speed, and prevent a free fall of the car in the event of broken suspension ropes.

The general inspection of overspeed governor shall cover the ropes running condition, condition of operative groove, presence of dirt and rust, and seal condition.

Overspeed governor [19]