ASME B56.11.6

Description / Abstract: This Standard establishes the conditions, procedures, equipment, and acceptability criteria for evaluating visibility from powered industrial trucks. It applies to internal combustion engine powered and electric high lift, counterbalanced, sit-down rider industrial trucks up to and including 10 000 kg (22,000 lb) capacity.

Visibility is evaluated by using an array of lamps, centered at the theoretical eye level of a seated operator, and observing light and shadow areas on a vertical screen in specific locations around the truck. The light source array simulates the normal range of position of the seated operator's eyes with typical head movement. The light and shadow areas describe what can and can not be seen by the operator. Traveling mode visibility is evaluated with the screen 4000 mm (157.48 in.) to the front of and to the rear of the truck. For maneuvering mode visibility, the screen is positioned at 1200 mm (47.24 in.) from the truck to the front, rear, and both sides. Acceptable visibility is based on measurements of dark shadows cast on the screen in each of the test conditions.