Spreader system for handling containers

Abstract

An improved radio-controlled spreader for handling cargo containers is disclosed having a number of improved safety features. A switching circuit, including proximity switches mounted on the respective corners of the spreader for sensing contact with the cargo container, controls the locking and unlocking circuits for twist locks which engage the container. The switching circuit prevents premature locking and accidental unlocking. The expansion and retraction circuit for the spreader includes swtiching means for controlling the flow of hydraulic fluid to the spreader in its expanded position which in cooperation with the hydraulic circuit prevent damage from external forces applied to the spreader ends. In addition, a backup safety circuit, which includes pressure switches in the hydraulic locking and unlocking circuit, is disclosed to reduce the possibility of excessive hydraulic pressure overcoming the lock position of the twist locks if the operator accidentally selects an unlock position while a container is suspended by the spreader and the proximity switches are out of adjustment. The mechanical, electrical and hydraulic aspects of these features are disclosed.

Dependencies are inferred from the claim text.