Linkage support system for material handling unit

Claim 1

In a material handling implement including a vehicle body, a boom pivotally supported on one end on said body with a boom fluid ram between said body and boom for pivoting said boom and a material handling unit pivoted on a free end of said boom by a unit fluid ram, the improvement comprising an arm supported on said body by a first pivot with said boom supported on said arm by a second pivot spaced from said first pivot; linkage means including first and second links pivotally interconnected at one end, said first link having an opposite end connected to said arm by a third pivot spaced from said first and second pivots and said second link having an opposite end connected to said boom at a location spaced from said second pivot, said unit fluid ram including a first element pivotally connected to said one end of said first and second links and a second element operatively connected to said material handling unit; and guide means between said body and said boom for guiding said boom during pivotal movement thereof, said guide means and pivots being positioned to pivot said arm between first and second extreme pivoted positions with said material handling unit being moved toward said vehicle as said arm is moved from said first extreme position toward said second extreme position, said arm being in said second extreme position when said boom is at an intermediate position generally parallel to a longitudinal axis of said vehicle body to minimize the moment arm for said boom at said intermediate position, said links being configured to maintain said material handling unit generally at the same angular attitude as said boom is moved from an extreme lower position to an extreme raised position.