1. Field of the Invention
This invention generally relates to digger and trencher equipment. More specifically, the present invention is a retractable assembly for use on portable diggers and trenchers used to add stability to the digger or trencher equipment while such equipment is in use.
2. Related Art
Many types of digger and trencher equipment ("trenchers") are disclosed in the prior art. These trenchers encompass many different types: from large, industrial trenching apparatuses used for the creation of very large and very deep trenches; to smaller, portable apparatuses used for smaller trenches. The present invention generally concerns portable diggers and trenchers, but may be used on industrial trenching apparatuses.
Of these portable trenchers, there are three main types: those which are an attachment for another vehicle or piece of equipment, those which have two main wheels and those which have four or more main wheels.
Portable trenchers can be attached to other vehicles and equipment. An example is U.S. Pat. No. 4,833,797 (Slunecka), which discloses a trencher attached to a steerable, self-propelled, wheeled tractor. The benefit in such an attachment is the fact that the trencher can be used anywhere a tractor can tow it. However, the need to use a separate vehicle, such as the tractor, to operate such a device greatly reduces the device's ease of use, and causes difficulties in using the device in confined places. Other examples of such attached equipment include: U.S. Pat. No. 4,483,084 (Caldwell); U.S. Pat. No. 3,834,049 (Bond); and U.S. Pat. No. 2,817,167 (Barber).
As mentioned above, portable trenchers may also have two main wheels. Such portable trenchers may also have a smaller, third wheel near the front of the trencher for added stability, as shown in U.S. Pat. No. 5,228,221 (Hillard). Other examples of portable trenchers with dual main wheels include: U.S. Pat. No. 2,997,276 (Davis); U.S. Pat. No. 3,087,354 (Malzahn); U.S. Pat. No. 4,322,899 (Clune); and U.S. Pat. No. 4,103,441 (Flippin).
The benefit of using a trencher with two main wheels is maneuverability. Being able to pivot on two wheels give such trenchers a very small turn radius, a feature that is very useful in digging multiple and curved trenches.
A drawback of such two main wheeled trenchers involves digging arch and kickback. As the bladed boom of the trencher is inserted and used in the soil to dig a trench, the front portion of the trencher in relation to the rear portion tends to raise up (digging arch) and jerk backward (kickback) when the bladed boom strikes buried stones and tree roots.
Finally, portable trenchers may have four or more main wheels. These trenchers range from small vehicles with built-in trenchers, to small, portable trenchers having four or more wheels. The benefit of having at least four wheels is that the trencher is very stable and does not suffer from digging arch or kickback to such a large degree as portable trenchers with two main wheels do. However, the drawback of such trenchers with four or more main wheels is the lack of ease of use and maneuverability, especially in tight corners or where multiple trenches and curves are required. Examples of such trenchers include: U.S. Pat. No. 4,913,581 (Weiler); U.S. Pat. No. 2,946,142 (Swanson); U.S. Pat. No. 4,896,442 (Stiff); U.S. Pat. No. 2,990,631 (Brown); U.S. Pat. No. 2,835,055 (Hermes); and U.S. Pat. No. 3,057,088 (George, et al.).
Thus, there is a need to create a trencher which combines the maneuverability and ease of use of the portable trenchers with two main wheels with the stability and resistance to digging arch and kickback of portable trenchers with four or more main wheels.