Vertical stockpicker manufacturer employs tilt switches
The non-contact sensors have rugged sealed housing and alert operator of unsafe conditions.
Mobile materials handling equipment, such as lift trucks and stockpickers, are not only subject to the wrong loading conditions or riding on non-level ground, but tip-over incidents, which have the potential of personnel injury, equipment damage and damage to materials and facilities.
Traditionally, companies have used mechanical measures to protect against these types of incidents, but non-contact sensors can now be used as OEM devices—built into or retrofitted to existing equipment—to alert an operator of unsafe conditions, so actions can be taken to avoid an accident.
A U.S.-based manufacturer of vertical stockpickers sought a better solution to limiting mast extension when its vehicles weren’t on level ground. It determined a mast can only be extended to a certain height safely when its vehicle is on an incline greater than 2 to 3 degrees.
The lift manufacturer had been employing mechanical pendulum style tilt switches. This type of sensor is typically preset with limits, is slow to react and can be prone to false alarms. The measurement of lift trucks’ inclination under static conditions is not the same as under dynamic conditions. In addition, the physics incurred with sudden acceleration or deceleration, in combination with fast turns, can cause a false alarm.
The manufacturer decided to employ non-contact DIS-Sensors tilt switches from one of its North American distributors. This style sensor is based on a solid state MEMS accelerometer chip, has a footprint of 1.6 x 1.6 inches and is housed in a rugged sealed housing. The entire unit is fully potted and sealed against environmental ingress.
A MEMS device, it is subject to forces imposed after sudden acceleration or deceleration, yet the manufacturer selected a DIS QG40N tilt switch since the unit could easily be fine-tuned, particularly by programming the parameters to minimize false alarms. The manufacturer can now fine-tune a number of parameters to best fit an application including alarm limits, pre-alarm limits, zero reference, sensor hysteresis, time delays, and sensor averaging.
While working with its distributor, the manufacturer determined the optimal settings and mounting location on the base of the stockpicker. It learned that the proper integration of sensors, primarily to improve safety, can enhance function—and it doesn’t need to be cost prohibitive or difficult to design into a product.
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