This design relates to an eccentric mounting and adjustment (EMA) system for belt driving, or for belt-driven devices, that is installed and operated within the restricted confines of an engine compartment, typically a motor vehicle. It satisfies two essential requirements for automotive devices driven by an endless flexible belt, including a reliable mounting to the engine block assembly, and a continuous provision of a proper amount of tension to the belt for either driving or driven devices. As a result, there is minimal wear and tear on device bearings and the belt, which reduces operational failures and assures maximum efficiency for these devices.

The system includes a housing fixed to the engine, a socket rotatable in pawl-and-ratchet fashion within the housing, and a socket aperture eccentrically disposed relative to the socket’s axis. The aperture receives the belt-engaging component, whereby rotation of the socket moves the component to adjust belt tension.

This innovation allows any flexible belt of the armed forces’ inventory to be readily removable, installable, and adjustable by a single person using the simplest of tools, such as a large screwdriver, a pair of pliers, or an elongated rod of about 0.5" in diameter. Thereby, former frustrations and expenses involving special tools or fasteners, which can be lost or misplaced, are avoided. Moreover, minimal force and exertion are expended.

This invention does not significantly modify or depart from standard procedures currently being used by motor pools for maintaining belts, drives, and driven devices. For example, electrical connections are easily made by using a simple bayonet or coaxial connector, that in form resembles the ends of modern “jumper cables” employed by the U.S. military, such that positive and negative poles are axially symmetrical. Similarly, connections for mechanical or hydraulic systems are just as easily made by conventional methods at the rear of this invention.

For military vehicles, belt performance is critical with regard to the tension that is maintained on them. With use, the belts can become loose and full torque is not easily transmitted to the driven devices. Thereafter, the belts can slip and become more damaged. If the belts are too tight, excessive wear can result in the bearing assemblies of the driving or driven devices as well as causing belt shredding or separation, which impacts operating efficiency. An eccentric adjustment and mounting system is useful for belt-engaging engine components such as alternators or water pumps.

This work was done by David N. Hansen for the Army Research Laboratory. For more information, download the Technical Support Package (free white paper) at  under the Mechanics/Machinery category. ARL-0091

This Brief includes a Technical Support Package (TSP).
Eccentric Mounting and Adjustment System for Belt-Driven Devices

(reference ARL-0091) is currently available for download from the TSP library.

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