Electric toe sensors are an option that is often provided on a dock lift that is to be installed into a recessed pit.
Electric toe sensors consist of a 4 sided steel bar assembly that is suspended by chains just below the underside of the dock lift platform. This 4 sided bar assembly is equipped with 4 electric limit switches that are wired in series in the closed position.
To lower the platform the dock attendant depresses the control station down button. Power to the electric operated lowering valve first travels from the push button down button through the 4 closed limit switches to the electrically operated lowering valve. The electric lowering valve opens and the hydraulic oil is now routed from the lift cylinders through the opened lowering valve back to the power unit reservoir causing the platform to lower.
As the platform is lowering should any object come in contact with the 4 sided steel bar assembly that is suspended just below the platform and cause the bar to rise slightly the lowering of the lift stops due to an open circuit on one or more of the 4 electric limit switches.
When one or more of the limit switches open circuits the electric signal to the lowering valve is interrupted and the platform stops lowering.
This link is to a photograph of a dock lift equipped with an optional electric toe sensor, see Page 7 https://www.pentalift.com/wp-content/uploads/2021/04/HED-Dock-Lift-Brochure.pdf
When the obstacle is removed and the sensor bar returns to its normal position and the operator depresses the down button, the platform will once again continue to lower.
For additional information on any Pentalift product please contact the Pentalift Sales Department.