The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 31, 1995
Filed:
Mar. 03, 1994
John Schoenmaker, Greene, NY (US);
Gene R Mathes, Binghamton, NY (US);
The Raymond Corporation, Greene, NY (US);
Abstract
The present invention features a method and an apparatus for preventing lift chains from becoming slack in a lift truck with a 'man-up' feature installed. Lift trucks are generally those vehicles that feature hydraulically controlled lift masts with a chain supported fork carriage. Operators of these lift vehicles with the remote lift and lower feature are generally lifted and lowered by these masts, known in the trade as a 'man-up' condition. It is quite desirable to prevent a slack chain condition in the man-up mast position. The invention features a pressure transducer for monitoring a drop in hydraulic fluid pressure established by the flow control valve that regulates the lowering speed of the mast during the remote mode, i.e., when the fork carriage is being lowered by the operator in the platform attached to the fork carriage. The invention turns off the normally closed load-holding valve when the hydraulic pressure drops below a predetermined value, which stops the flow of hydraulic fluid back into the reservoir. This, in turn, stops the cylinder(s) from lowering and keeps the fork carriage lift chains from becoming slack.