Caterpillar Inc.

Phillip W Alexander

Michael Steven Freberg

James E Johnston

Keith A Howell

Method and apparatus for selectively tensioning an endless, inextensible elastomeric belt entrained about a cooperating drive structure and idler structure having respective axes of rotation. A roller frame joined to a vehicular main frame supports the idler structure and constrains movement thereof to a longitudinal recoil path. The drive and idler structures are biasingly separated by a compression spring which exerts biasing force thereon in opposite longitudinal directions through a drive strut and an idler strut, respectively. The idler strut is connected to the idler structure longitudinally in front of the idler's axis. The length of one of the struts is adjustable to provide the desired tension in the spring and, thus, the entraining belt. Increases in tension are preferably provided by displacing one component member of the one strut relative to a second component member thereof-one of such members being reciprocatably receivable in the other and provided with a seal therebetween such that the two members cooperatively define a pressurizable chamber. Pressurized fluid, when transmitted into the pressurizable chamber, provides relative longitudinal displacement of the two members so as to decrease the spring and belt tension. A locking assembly threadably engaged with one of the members is rotated until it abuts the other member and permits the fluid pressure to be reduced while maintaining the length of such adjustable strut.

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Davenport, IA, United States of America

Phillip W Alexander