Tandem hydraulic actuator

Claim 1

A fluid actuated cylinder comprising: a housing having a cylindrical bore; gland means dividing said cylindrical bore in said housing into a first chamber and a second chamber; an end wall, having an internal tail rod with an area `A` closing said second chamber of said housing; a first piston for movement in said first chamber; a second piston for movement in said second chamber; rod means penetrating said gland means, operatively connecting said first piston to said second piston in tandem, said pistons are axially aligned and moveably disposed in their respective chambers to move in cooperation between extend and retract positions with one end of said rod means having a bore to accommodate said internal tail rod, an output rod connected to said first piston having an area `A`, extending from said first chamber; a rod end wall closing said first chamber of said cylindrical bore in said housing and having a bore therein to accommodate said output rod extending from said first chamber; and means for admitting pressure fluid against a first pressure surface on one side of said first piston and second pressure surface on one side of said second piston while exhausting fluid acting on a third pressure surface on the opposing side of said first piston and fourth pressure surface on the opposing side of said second piston so as to move said pistons in either direction, alternatively, the first and fourth pressure surfaces being equally dimensioned and the second and third pressure surfaces being equally dimensioned, whereby to define a fluid actuated, tandem, linear actuator having redundant chambers and equal combined areas in both extend and retract positions.