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:
Nov. 21, 1995
Filed:
Jun. 07, 1994
Todd D Creger, Metamora, IL (US);
Randall M Mitchell, Washington, IL (US);
Alan L Stahl, Peoria, IL (US);
James R Talbott, Fitchburg, MA (US);
Caterpillar Inc., Peoria, IL (US);
Abstract
In one aspect of the present invention, an electronic shift control for a powershift transmission is disclosed. The transmission includes a plurality of speed and direction changing clutches. A plurality of pressure control valves are individually connected to the clutches. A hydraulic pump delivers pressurized hydraulic oil to predetermined pressure control valves to meter hydraulic fluid in response to receiving a clutch command signal. The method produces a shift from a first transmission ratio to a second transmission ratio through disengagement of an off-going clutch associated with the first transmission ratio and engagement of an on-coming clutch associated the second transmission ratio. The method includes filing an on-coming speed clutch, releasing an off-going direction clutch in response to the on-coming speed clutch being filled, and thereafter, gradually increasing the on-coming speed clutch pressure to engage the speed clutch. Finally, the on-coming direction clutch pressure is gradually increased to engage the direction clutch in response to the on-coming speed clutch being engaged.