Compacting machine having variable vibration

Claim 2

A machine for compacting soil and the like, said machine having a drum that rotates about its axis in rolling over the surface of material to be compacted, a member driven for rotation about an axis parallel to that of the drum, eccentric mass means carried by said member, and means operatively connecting said member with the drum to impart thereto surface compacting vibration produced by rotation of the eccentric mass means, said machine being characterized by: A. motor means for rotatably driving said member; B. control means for said motor by which its speed and direction of rotation may be selected and controlled; C. means mounting the eccentric mass means on said member for motion relative to the member toward and from the axis about which said member rotates but constraining the mass means to rotate with said member; D. fluid pressure means so connected with said eccentric mass means as to opposte centrifugally responsive motion thereof relative to said member and in which pressure of fluid is increased by increased centrifugal force upon the eccentric mass means; and E. overspeed preventing means comprising a pressure responsive element connected with said fluid pressure means to be responsive to fluid pressure therein and operatively connected with said control means to interrupt operation of the motor when pressure of fluid in the fluid pressure means exceeds a predetermined value.

Claim 3

A variable amplitude vibration producing device for soil compaction and the like, comprising: A. first and second mass elements; B. means mounting said mass elements for rotation in counterbalancing relation about an axis, with the first mass element fixed with respect to said axis and the second mass element movable towards and from said axis between defined inner and outer limits, so that the amplitude of vibration resulting from rotation of said mass elements depends upon the location of said second mass element with respect to said axis; C. hydraulic cylinder and piston means connecting said mass elements with the cylinder fixed with respect to one mass element and the piston fixed with respect to the other mass element, so that the mass elements can not move relative to one another without corresponding relative movement between the piston and cylinder; D. a yieldable fluid pressure source E. a closed hydraulic circuit having connected therein the yieldable fluid pressure source and the space in the cylinder at the side of the piston that faces the mass element with respect to which the piston is fixed; F. hydraulic fluid in said closed circuit filling said space in the cylinder and manifesting in said space the pressure of said yieldable fluid pressure source, the yieldable fluid pressure source maintaining the hydraulic fluid under a pressure that is sufficient to hold the movable second mass element at its inner limit of movement when the mass elements are not rotating, but insufficient when the mass elements are rotating above a predetermined speed, to prevent displacement of hydraulic fluid from the cylinder and consequent movement of the movable second mass element towards its outer limit of movement in response to centrifugal force acting thereon; and G. control valve means in said closed hydraulic circuit between the cylinder and the yieldable fluid pressure source operable to either prevent or permit hydraulic fluid to be displaced from the cylinder.

Claim 4

A variable amplitude vibration producing device for soil compaction and the like, comprising: A. first and second mass elements; B. means mounting said mass elements for rotation in counterbalancing relation about an axis, with the first mass element fixed with respect to said axis and the second mass element movable towards and from said axis between defined inner and outer limits, so that the amplitude of vibration resulting from rotation of said mass elements depends upon the location of said second mass element with respect to said axis; C. hydraulic cylinder and piston means connecting said mass elements with the cylinder fixed with respect to one mass element and the piston fixed with respect to the other mass element, so that the mass elements can not move relative to one another without corresponding relative movement between the piston and cylinder; D. a yieldable fluid pressure source E. a closed hydraulic circuit having connected therein the yieldable fluid pressure source and the space in the cylinder at the side of the piston that faces the mass element with respect to which the piston is fixed; F. hydraulic fluid in said closed circuit filling said space in the cylinder and manifesting in said space the pressure of said yieldable fluid pressure source, the yieldable fluid pressure source maintaining the hydraulic fluid under a pressure that is sufficient to hold the movable second mass element at its inner limit of movement when the mass elements are not rotating, but insufficient when the mass elements are rotating above a predetermined speed, to prevent displacement of hydraulic fluid from the cylinder and consequent movement of the movable second mass element towards its outer limit of movement in response to centrifugal force acting thereon; and G. control valve means in said closed hydraulic circuit between the cylinder and the yieldable fluid pressure source operable to either prevent or permit hydraulic fluid to be displaced from the cylinder.

Claim 5

The invention of claim 2, further characterized in that said first mass element has a moment greater than the largest moment that can be exerted by the second mass element.

Claim 6

The invention of claim 2, wherein said yieldable fluid pressure source is a pressure accumulator.

Claim 7

The machine of claim 2, further characterized by: F. a motor by which said mass elements are rotatably driven; G. control means for said motor by which its speed and direction of rotation may be controlled; and H. overspeed preventing means comprising a pressure responsive element connected with said cylinder to respond to fluid pressure therein that is produced by centrifugal force acting on the first mass element and having an operative connection with said control means by which operation of the motor is interrupted when such centrifugal force exceeds a predetermined value.