Abstract: A seal is attached to and curved around a floating roof of a storage tank for petroleum products or other liquid materials, to extend to an outer circumference at the tank wall. The curved seal is suspended at first suspension points on the seal spaced about the floating roof. These first suspension points are spaced from the mentioned outer circumference at the wall by a first distance greater than zero and from the floating roof at a second distance greater than such first distance. The curved seal is suspended at these first suspension points from a series of corresponding second suspension points spaced from the first suspension points by third distances. Each of the second suspension points is spaced from the tank wall by a fourth distance greater than zero and from a peripheral cylindrical reference surface about the floating roof by a fifth distance greater than the mentioned fourth distance.

Abstract: A vertical drill rig is provided with a hydraulic crowd mechanism for crowding down a drive kelly having a rotating drilling tool supported from the lower end thereof.The crowd mechanism includes a drum having first and second cables wound in opposite senses thereon. The drum is rotated by a hydraulic motor driven by pressure regulated fluid supplied by an accumulator charged with fluid received from a hydraulic pump. The cables couple the drive kelly to the rig such that, when the hydraulic motor rotates the drum in a given direction, the first cable is paid out to lower the drive kelly while the second cable is simultaneously taken up to crowd down the drive kelly relative to the rig. Such a construction and arrangement provides a substantially constant crowd down force on the rotating drilling tool irrespective of its vertical rate of penetration into the earth.

Abstract: A support system for a boom mounted on a truck includes four outriggers mounted to the boom pedestal which can be folded against the pedestal or extended to provide a wide base for supporting the boom. Each outrigger has an inboard leg member pivotally mounted to the truck and driven by a hydraulic cylinder. An outboard leg member is pivotally mounted to the outer end of the inboard leg member and is caused to pivot relative to the inboard leg member at approximately twice the pivot rate thereof and in the opposite direction. The outriggers may be extended by a single operation of the hydraulic cylinder. The means for rotating the outboard leg member causes the outrigger not to drag along the ground until it is finally placed. Means are provided for preventing pivotal motion of the legs beyond predetermined positions.