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WCB Standards

WCB Standard: G605 Mobile Equipment Half-Doors, March 1990

© Workers' Compensation Board of British Columbia. All rights reserved. No part of this document may be copied, reproduced, or distributed for profit or other commercial enterprise, nor may any part be incorporated into any other publication, without written permission of the Workers' Compensation Board of B.C.

1. General

1.1. Scope
This standard pertains to any rubber-tired skidders employed in the skidding of logs or tree lengths where the operator may be exposed to flying or other intruding objects.

1.2. Supplementary References
This standard is supplemented by G604 WCB Standard for Light-Duty Screens.

1.3. Purpose
This standard is intended to describe the minimum requirements for the design and selection of structural elements such as plates, stiffeners, sheer deflectors, spring latches or hinges for the half-door.

2. Design Requirements

2.1. General Location
A half-door shall be installed on both side entrances to the control area.

2.2. Dimensions
The entrance opening width shall be a minimum of 46 cm (18 inches). Recommended opening width is 70 cm (27 inches).

The door height shall be a minimum of 60 cm (25 inches) from the floor and having the top of the door at least 25 cm (10 inches) above the cab seat.

2.3. Character (Distinctive Qualities)

The half-door should not sweep the area of the platform or the steps on which the operator must stand to open the door. It shall sweep outward from the cab.

The half-door shall be equipped with a device to cause it to return to its closed position automatically. Also, a latch, preferably of pressure sensitive type should be used to lock the door.

There should be sufficient clearance between the maximum radius of door sweep and the rubber tires of the mobile equipment.

A sheer deflector or stiffener shall be installed on the exterior top edge of the door to act as a deflector/stopper for objects propelled upward.

2.4. Static Strength

The top edge of the door shall be reinforced by a ledge, (sheer deflector), a structural element capable of withstanding a concentrated force of 17800 N (4,000 lbs.) applied at 45 to the horizontal.

Any area of the door shall be designed to resist a 17800 N (4000 lb) static force applied over an area of 62 cm2 (9.6 in2).

The hinges, stops and supports shall be adequately designed and fabricated to resist any loads that the door would likely impose upon them. The entire door assembly shall be designed to resist a static force of 17800 N (4,000 lbs.) without causing the door to spring open. On vehicles equipped with a ROPS (Rollover Protective Structure), the door-supporting elements may be attached to parts of the ROPS providing such attachment does not adversely affect the performance of the ROPS. This is contingent on approval by a registered professional engineer.

Weldments shall conform to applicable sections of General Specifications for Welding of Steel Structures CSA W59.1-1970 or most recent version and should be performed by qualified welders only.

2.5. Impact Strength Requirement
All members of the half-door shall be fabricated of material with good impact absorbing properties. The following guideline may be used:

  • Low carbon content - maximum .28%
  • High manganese-carbon ratio
  • Low phosphorus content
  • Fine grain size
  • Heat treated
  • High ultimate energy resistance (Notch tough steel possessing acceptable impact properties)

Examples of steel meeting or exceeding the above requirements:

  • ASTM A36 or CSA G40.21-38W - for bars, angles and plate
  • CSA G40.21 42W, 55W - for HSS (Hollow Structural Sections) (CSA G40.16 and G40.17)
3. Structural Details Guidelines

The following recommendations may be used in lieu of clause 2.4.1 and clause 2.4.2

Minimum ledge beam size shall be 2 x 2 x .188 HSS, CSA G40.21 42W.

Door - steel plate 5 mm (3/16") minimum.

Minimum intermediate stiffener size shall be L 2 x 2 x 3/16 CSA G40.21 33W.

Maximum spacing of stiffeners is six inches, when L 2 x 2 x 3/16 is used.

Illustration - G605 Half Door (Typical)

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