GB1461916A - Vehicle with retractable guard - Google Patents

Abstract

1461916 Vehicle safety devices CROWN CONTROLS CORP 26 Feb 1974 [26 Feb 1973 7 Feb 1974] 8721/74 Heading B7B A fork lift truck is provided with an overhead guard 118 which is movable to a stowed substantially upright position in front of the operator. The front corners of the guard are pivoted to uprights 122, 123 telescopically received in lower uprights 119, 120, the uprights being telescoped by an hydraulic ram assembly 132, 134. The rear of the guard is mounted by pivotally interconnected members 124, 126 which cause the rear edge of the guard to pivot upwardly about the front edge as the front uprights are telescoped. Each upright 122, 123 carries a chain 144 which meshes with a respective sprocket 138 carried by a shaft 136 mounted on uprights 119, 120. An electrical circuit for controlling the hydraulic ram assembly is provided (Fig. 6, not shown), the circuit including solenoid control valves and a pressure sensitive switch (76) which opens to shut off pressure supply when the ram reaches the end stroke positions. Apparatus is provided for controlling the operation of the fork 150 and guard so that the guard cannot be lowered when the fork is above a given height and so that the fork cannot be raised above a predetermined height when the guard is lowered. A control circuit, Fig. 10, includes a switch 164 on upright 119 which is opened as upright 122 is lowered and a switch 152 on the fork mast which opens when the fork is raised above a predetermined height. With both the fork and guard lowered switches 152 and 164 are respectively closed and opened and a relay 178 is energized to close relays RC1, RC2. To raise the guard a selector switch 174 is moved to the left actuating a guard raise solenoid 184 and allowing hydraulic fluid to flow through a valve to the hydraulic ram assembly. When the guard is raised pressure in the ram assembly opens pressure switch 176 to de-energize solenoid 184. The fork may now be raised by closing switch 186 energizing a valve controlled by solenoid 188 and a lift pump solenoid 192 connected to switches 152, 164. As the fork goes above a predetermined height switch 152 opens but solenoid 192 remains energized since switch 164 is closed with the guard raised. With both fork and guard raised switches 152, 164 are respectively open and closed hence the guard cannot be lowered since solenoid 196 cannot be energized until the fork is lowered to close 152. The fork may be operated whilst switch 164 remains closed. When the guard is lowered switch 164 opens and the fork may only be raised to the height at which switch 152 opens.