Elevator Jolting Expert Article

Elevator experts are often contacted about an elevator “jolting.” Jolting is a term used by plaintiffs for a variety of ride quality issues that are experienced while riding an elevator. These can include sudden stopping, reversal of direction, and shaking or other erratic ride qualities, which can result in injuries due to falls and loss of balance.

In this article, elevator expert Michael Vallone will describe common causes of the “jolting” sensation on an elevator, and how the cause can be determined in a forensic investigation.

Elevator Jolting Expert Witness Investigations

What Causes Elevator “Jolting”?

Tripped Interlock

The sensation of “jolting” may occur if an elevator trips an interlock during travel. The interlock is an elevator component that is attached to the hoistway door and keeps the hoistway door from opening when the elevator is not present. The interlock consists of a mechanical component that blocks the door from opening and an electrical component that is wired into the safety circuit of the elevator controller.

When the elevator is present, the door clutch that is attached to the elevator door will engage the interlock and open the door. If the interlock or clutch are misaligned the clutch can open the interlock, and therefore safety circuit, as the elevator is traveling past the interlock. This opening of the interlock will cause the elevator to briefly stop.

Generally, the elevator will continue past the interlock as it is stopping and the lock will reengage, which completes the safety circuit and allows the elevator to continue its normal operation. This brief stop gives the passenger a feeling that the elevator jolted or stuttered.

Emergency Stop

Another cause of “jolting” could be an emergency stop. An emergency stop is caused when an elevator operates so far outside its parameters that the elevator has no choice but to take itself out of service.

An emergency stop does not stop the elevator as it would under normal operation, where the elevator would utilize the controller to reduce the speed of the motor to stop and then set the brake that holds the elevator in its stopped position.

During an emergency stop, an elevator stops by dropping the brake and using the brake to stop. An emergency stop of an elevator can be hard and abrupt. An emergency stop of the elevator can be described as “jolting.”

Change of Direction

The elevator can also unexpectedly change direction and cause a passenger to experience a “jolting” sensation. The change of direction can be caused by a number of reasons, including:

  • The elevator going into firefighter’s service operation
  • The passenger entered an elevator traveling in the wrong direction
  • A power outage and the elevator enters emergency power operation, etc.

This change of direction when not expected can be “jolting” to the passenger.

Shaking from Mechanical or Electrical Components

An elevator shaking during travel can be caused by mechanical components of an elevator, such as a worn-out or improperly adjusted roller guide. The roller guides are the wheels attached to the elevator that make contact with the rails while the elevator is running.

An example of an electrical component that could cause an erratic ride quality would be an encoder. The encoder is a component that attaches to the motor and gives feedback to the elevator controller about the position of the elevator in the hoistway.

If the encoder wears out or is installed improperly, the feedback that it gives to the elevator controller can cause the elevator to run erratically or cause the elevator to lose its position in the hoistway. This erratic operation or loss of position can include shaking or stuttering of the elevator during travel.

Investigating Injury-Causing “Jolting” Events

Elevator passengers expect a smooth ride quality and for the elevator to travel continuously, except for controlled stops to pick up other passengers. When one of these “jolting” events happen it can cause injuries due to loss of balance and falls. These injuries are generally due to the unexpected nature of the “jolting” of the elevator.

In a forensic investigation of a “jolting” incident, a review of the service records for the elevator will provide insight as to what the history of the elevator entails. This includes any maintenance, repairs, inspections, and testing.  These service records can sometimes not be fully accurate and a site inspection can verify that what is in the records is physically on site.

For more information, submit an inquiry or call us at 800.813.6736.

Featured Expert

Michael Vallone, Elevator & Escalator Expert

Michael Vallone, C.E.I.

Elevator & Escalator Expert
Michael Vallone is an elevator and escalator expert with over 20 years of industry experience as a field mechanic, maintenance supervisor, and operations manager. His expertise extends to all aspects… read more.


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