1. Field of the Invention
The present invention relates to small, chain-driven carts (sometimes referred to as "go-carts"), and the like having an internal combustion engine of, for example, five-ten (5-10) horse power that drives the cart rear wheels via an axle and centrifugal clutch. Even more particularly, the present invention relates to an improved engine shaft, clutch, and chain-driven axle assembly for powering small motorized carts wherein an improved lubrication arrangement allows grease to be injected through an engine drive shaft (or a short intermediate shaft or "jack" shaft) of the cart via a porting system so that the clutch is lubricated when rotating at high speeds, namely, when the cart is at rest and the engine idles.
2. General Background
Small chain-driven motorized carts are commercially available from a number of manufacturers. These carts are used primarily for off road motoring at relatively low speeds. They are frequently used for backyard and off road family fun, and can be found at amusement parks and fairs on occasion.
These small chain-driven carts include a metal frame that is generally of welded steel, using square and round tubing and plate steel, for example. Such small carts use an internal combustion engine for power, usually on the order of five to ten (5-10) horse power, as an example. The cart frame is constructed very low to the ground for stability purposes. The engine on such a cart is usually a commercially available internal combustion engine, having a drive shaft that carries a centrifugal clutch. A sprocket on the clutch engages an endless belt or chain. Another sprocket rigidly affixed to the axle also engages the endless belt or chain. When the engine of the cart idles, the centrifugal clutch by design is disengaged. When the user presses a throttle (e.g., foot pedal) the engine revolutions increase and the clutch engages so that the sprocket of the clutch rotates and drives the endless belt or chain and its associated axle sprocket and attached axle.
By placing the cart low to the ground, equipping the cart with relatively small wheels, and by using the cart in a off road environment, the centrifugal clutch is subjected to dirt, sand, dust, and debris which accumulates in and around the clutch assembly. This produces an abrasive environment which can quickly wear out the clutch parts. The centrifugal clutch is typically rotated at high speeds when the cart idles. The clutch engages upon increasing engine revolutions so that centrifugal members engage the clutch and it forms a rigid connection with the drive shaft of the cart.
Typically, these carts use a horizontal shaft engine. The drive shaft extends horizontally from one side of the engine. However, it should be understood that a short separate intermediate drive shaft sometimes referred to a "jack-shaft" can be used to drive the carts. A "jack-shaft" is simply a short shaft mounted between bearings and in spaced-apart position away from the horizontal shaft of the engine. The "jack-shaft" is driven by the motor shaft using a belt or sprockets and a chain, for example. In either situation, the present invention is designed to provide an improved lubrication arrangement for the engine shaft, and/or a "jack-shaft" used with the engine drive.