Section 21.41. Trolley and side-rolling ladders

(a) It is recommended that trolley ladders and side-rolling ladders over 20 feet in length not be used.

(b) The dimensions of side rails shall not be less than that shown in the following table; the required thicknesses provided for the cutting of a gain not over 1/8 inch in depth and shall be increased when gains of greater depth are used:

Length of Side Rails (feet)	Thickness (inches)	Depth (inches)
Up to and including 10	25/32	3
Over 10, and up to and including 20	25/32	3 1/4

(c) It is recommended that locking devices be provided on all trolley ladders.

(d) Tracks shall be of wood, or metal, except cast iron, or a combination of these materials.

(e) Tracks for the top end of ladders shall be fastened securely and so constructed that the wheels do not jump the track. Tracks shall be so designed as to provide for all probable strains to which they may be subjected.

(f) The supports shall be securely fastened by lag screws, machine, hook, or toggle bolts or their equivalent.

(g) Tracks for side-rolling ladders shall be supported by metal or wood brackets securely screwed or bolted to shelving or another permanent structure at not over 3 feet on centers.

(h) Wheel carriages shall be so designed as to provide for all strains to which they may be subjected. It is recommended that two point suspension be used. The wheel carriage for the top end of the ladder shall be securely fastened to the top of the ladder with metal brackets bolted either to the side rails or to the top step. When bolted to the top step this step shall be secured to the side rails with metal braces in addition to those otherwise provided. The wheel carriage shall be so designed that a loose or broken wheel does not allow the ladder to drop or become detached from the track.

(i) The wheel carriage for the bottom end of the ladder shall be securely fastened to the bottom of the ladder.

(j) The wheels at the upper end of the ladder shall have a minimum wheel base of 8 inches. When wheels are used at the bottom of the ladder there shall be at least one wheel supporting each side rail.

(k) Running gear for bottoms of both trolley and side-rolling ladders shall be so designed and constructed as to provide for any strain to which they may be subjected.