Abstract: A power driver and method of pile driving. The invention encompasses a pile driver having a ram, cylinder and piston arrangement mounted in a framework, such arrangement being typical of those power drivers of the prior art. A compressible fluid, such as air or steam, enters into the cylinder through an intake port and leaves through an exhaust port. Both ports are controlled by a common valve. Expansion of the steam within the cylinder acts against the piston causing the piston rod to rise thus raising the ram and an associated slide bar. As the slide bar rises, it triggers the valve to move into a position effecting closure of both intake and exhaust ports. Further rising of the piston effects movement of the valve into a position wherein the intake port remains closed and the exhaust port is opened, thus exhausting the excess steam. Movement of the valve by elevation of the slide bar at each stage of movement is effected through triggering of cam followers or trips by cams on the slide bar.

Abstract: An improved pile driving cap block cushion material is the subject of this invention. The material is a thermoplastic material characterized by being in particulate form, fiber filled (preferably glass fiber filled), having a melting point of 125.degree. C. or higher, a secant modulus of elasticity of from 50,000 to 800,000 p.s.i. and a coefficient of restitution of from 0.4 to 0.9. A number of thermoplastic materials are suitable for forming the material of the invention and include polyamides, polyesters, polyolefins, polycarbonates, polyimides, polyamide-imide copolymers, acetal homopolymers, acetal copolymers, fluoroplastics, polyphenyl oxides, copolyesters, polyetherimides, polystyrenes, polyvinyls, and polysulfones. A particularly useful group of materials is poly(ethylene terephthalate), poly(butylene terephthalate), nylon 6 and nylon 66. Additives such as antioxidants, heat stabilizers, reinforcers and colorants may also be added.

Abstract: An improved pile driving cap block cushion is the subject of this invention. The material is a glass filled thermoplastic characterized by a melting point of 125.degree. C. or higher, a secant modulus of elasticity of from 50,000 to 800,000 p.s.i. and a coefficient of restitution of from 0.4 to 0.9. A number of thermoplastics are suitable for forming the material of the invention and include polyamides, polyesters, polyolefins, polycarbonates, polyimides, polyamide-imide copolymers, acetal homopolymers, acetal copolymers, fluoroplastics, polyphenyl oxides, copolyesters, polyetherimides, polystyrenes, polyvinyls, and polysulfones. A particularly useful group of materials is poly(ethylene terephthalate), poly(butylene terephthalate) nylon 6 and nylon 66. Additives such as antioxidants, heat stabilizers, reinforcers and colorants may also be added.

Abstract: An automatic, fluid actuated, external control system for a pile hammer or the like is provided that can vary the operating stroke length of a pile hammer and that can be used to operate the pile hammer in either a continuous or single stroke mode. A series of axially spaced orifices in the hammer housing exhaust pressurized fluid from the housing in a sequence controlled by the position of the hammer piston within the housing. The orifices are coupled by conduit to a series of pressure sensitive valves external of the pile hammer. The pressure sensitive valves control the delivery and exhaust of pressurized motive fluid to and from the pile hammer in response to the position of the hammer piston within the hammer housing.

Abstract: In a pile driving hammer including a striker elevatable on guides by fluid pressure delivered to an operating fluid cylinder, and capable of being dropped to deliver a pile driving blow by exhausting fluid from the cylinder, a control system for the cylinder including a first cam carried by the striker and operable to cause delivery of fluid to the cylinder at the lower end of the stroke of the striker, a plurality of second cams carried by the striker and operable to cause exhaust of fluid from the cylinder at respectively different elevations of the striker, and remotely controlled apparatus for activating any selected one of the second cams.