Vertical Analysis - Escalator Safety (Standard Inspection Methods)

Vertical Analysis LLC

6801 Marlboro Pike

Forestville

Maryland 20747

1(800)447-3344


	Identifying Worn, Damaged or Defective Step Components

The standard method for identifying worn or damaged step components involves walking on the steps and feeling for excess movement with your feet.

A17.2.3b 1997, item 1.9 - Steps and upthrust device

...(b) Check at least every tenth step by riding on it, to determine if the following requirements are met:

(1) There is no excessive movement or play in the direction of travel and vertically. While standing on the step a lateral shift of weight should not cause the step to strike the skirt panels.

This only checks every tenth step, and has a huge margin of error. Often this technique will only be reliable in detecting extreme conditions that have far exceeded what would be considered as safe.

In comparison, the Vertical Analysis Step Defelection Test makes upto 60 measurements per second, accurately profiling every step, to a resolution of 4/1000”.


	Checking Step and Combplate Mesh

The standard method for checking step and combplate mesh is to hold a business card at the point where the step enters the comb to see whether it is drawn into the machine.

A17.2.3b 1997, item 1.7 - Combplates

Inspect the comb for missing teeth and proper mesh with each step tread. Verify proper mesh with each step tread by holding a sheet of stiff paper or a business card where the teeth mesh with the step tread, while standing well back from the plate to prevent forcing the plate down. Use of an extension with an alligator clip to hold the card is recommended.

This test only checks for minimal mesh (marginally better than 0”) as required by the A17.1 code.

A17.1a 1997, rule 802.6a - Combplates

...(2) The comb teeth shall be meshed with and set into the slots in the tread surfaces so that the points of the teeth are always below the upper surface of the step treads.

This test, however, may be ineffective because there is no load applied to the steps during testing. This means that problems, such as worn or soft rollers, that may cause inadequate mesh under load, are often not identified.

Additionally, most manufacturers as with many international standards require a mesh in excess of 3/16” (4.8mm). The business card test can in no way verify that.

In comparison, the Vertical Analysis Step Defelection Test applies a load to the step, and refereces the position of every step to the bottom of the comb teeth. This means that mesh can be checked under normal operating conditions, and verified against both the A17.1 code and the manufacturers specification. This is the only accurate method of identify comb-step mesh problems.


	[Home] [Accidents] [Solutions] [Industry News] [Statistics] [About VA] [Links]