In the prior U.S. Pat. No. 3,279,559 of C. M. Hirst, Jr. issued Oct. 18, 1966, there is disclosed a cushioning and locking mechanism for tilt cab vehicles including bell crank cam means for initially displacing a hook member axially from a locked position relative to a fixed locking pin to a safety position spaced from the pin, and for subsequently pivoting the locking member to a fully released position relative to the pin. In another prior U.S. Pat. No. 3,497,257, of the same inventor entitled "Tilt Cab Lock Actuator" issued Feb. 24, 1970, an improved locking system is disclosed that is operable hydraulically by piston-cylinder motor means, thus permitting remote control operation of the tilt cab locking means. One drawback of the above mentioned devices was that the hook member could move to the fully locked position without engaging the locking pin, particularly when the vehicle was on uneven ground, thereby preventing the locking components from being properly seated.
In another U.S. Pat. No. 3,581,840 issued June 1, 1971 to C. M. Hirst, Jr. and Eugene C. Lipshield, there is disclosed a tilt cab lock actuator including provisions which prevent the hook member from moving to the fully locked position without first engaging the locking pin when the locking components are in a jammed condition. Although the latter invention functions quite well, it consists of a large number of parts which are quite costly, as well as difficult to assemble. In each of the previously mentioned inventions, the lock assembly includes a movable hook which engages a stationary locking pin.
The present invention was developed to provide an improved locking mechanism which avoids the above and other drawbacks and which is less costly to produce and consists of a reduced number of parts that are readily assembled.