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:
Jun. 27, 1989
Filed:
Apr. 28, 1988
Mazda Motor Corporation, Hiroshima, JP;
Abstract
The multistage transmission gear mechanism is provided with a first and second coupling means for shifting speed stages, each being of a type operable hydraulically and adapted to allow four speed stages from first to fourth speed stages to be selected in accordance with a combination between a coupled state and an uncoupled state of the first and second coupling means. A third coupling means is further provided for ensuring engine braking. The second coupling means is engaged or coupled by a first pilot pressure generated by a first solenoid at the second, third and fourth speed stages. The first coupling means is coupled by a second pilot pressure generated by a second solenoid at the third and fourth speed stages. The third coupling means is coupled at the second and third speed stages. A third solenoid is provided for generating a third pilot pressure which prevails over the first pilot pressure and controls shifting the second coupling means at the third speed stage. At shifting between the second and third speed stages, the second pilot pressure prevails over the first pilot pressure to being the second coupling means into a state of its shifting being controlled by the third pilot pressure. At this time, shifting the third coupling means is controlled by the first pilot pressure to avoid a temporary engagement of all the three coupling means, thus preventing a transmission shock.