The forklift's turning radius is also known as the turning circle, that is vital information for the driver to have. It gives the driver the knowledge of how much space is required to turn the lift truck around. For example, a tighter turning radius allows the machine to work successfully in crowded areas and restricted places, thus enhancing the lift truck's maneuverability. Operators who do not know this measurement can cause damage to the machinery or to the property.
Prior to testing the turning radius, check the steering geometry alignment and correct it if it requires adjustment. Start the test with having the trained driver inside the cab to control the machine's functions. A second person on the ground uses a spray bottle or a hose to wet the inside and outside of the unit's wheels. Then, drive the machinery in a whole circle with the wheels turned to the maximum angle. Repeat the procedure once and if necessary, continue to wet the wheels.
After this measurement test has been done, measure the watermarks left by the tires with a tape measure, from the midpoint of the tire mark to a similar point across the circle's diameter. For the outside turning diameter, measure the watermark left by the outside tires from the circle's one side to the opposite side of the circle. The inside turning diameter can be determined by stretching the tape measure across the circle left by the interior tires. Next, divide these numbers in 2 in order to establish the turning radius. Be sure to note that the turning center is the midpoint of the diameter of the circle.
Drop a plumb line from the extreme outside radial extension on the machine in order to determine the wall-to-wall turning diameter. When this is accomplished, next find the point on the pavement directly beneath. This point to the turning center indicates the equipment clearance radius. As a rule, wall-to-wall turning diameter is two times the machinery clearance radius.