1. Field of Art
This invention relates to the improvement of a steering column in the cab of an agricultural combine harvester. More specifically it relates to a steering column which may be adjusted in four directions.
2. Description of Prior Art
Mechanical harvesting of grain has taken place for decades. However, efforts continue in the attempt to make harvesting operations more efficient and effective. A combine harvester generally includes a head which cuts the crop. The head than moves the cut crop into a feeder house. The feeder house lifts the cut crop into the threshing and separation areas of the combine. The grain is separated from the stalk by a rotor. The grain is then moved and stored in a grain tank. The chaff and trash is deposited from the rear of the combine. An operator usually runs these various operations from a glass-enclosed cab. Typically, a cab is located behind the head and in front of the threshing and separation areas of the combine. An operator can observe most of the combine activities from the cab. During harvesting periods it is not uncommon for the combine to be operated for an extended time. Sometimes a single operator will use a combine for 16 to 18 hours a day. Furthermore, several operators may alternate in the use of the combine. Therefore is it necessary to provide a cab which will allow maximum operator comfort and flexibility. This will permit the operator to remain mentally alert for the long time intervals needed to harvest crops. One aspect of maintaining the operator's alertness is to provide a steering column that may be manipulated to a comfortable position. Equally important is to provide a steering column which is located in a manner to allow an unobstructed view of the various combine operations. It would also be advantageous to provide a steering column which would be suitable to different sized individuals. Finally it would be desirable to provide an steering column that is relatively impervious to the harsh off-road environment common in farming operations.
The effort to design and manufacture an acceptable steering column for farm operations is considerable. The research effort has followed several paths. Many steering columns use a single telescoping portion. This feature allows the steering wheel to be moved either closer or further from the operator. An additional improvement provides for a pivot assembly to allow the column to be positioned in a variety of angles. Initially, a ratchet mechanism has been used to control the pivoting motion. Later, gas cylinders were introduced to allow the steering column to be positioned in infinite range of angles. However, each of these approaches has limitations and drawbacks. Typically, these steering columns were placed in automobiles into a vertical wall, such as the firewall. Therefore, it is necessary to provide only a steering column with two ranges of motion (rotation around the pivot axis and translation along the steering column). However, in a harvester combine such a design is undesirable. The placement of a steering column on a vertical surface would obstruct the operator's view of the header. It is possible to affix a steering column to the horizontal cab floor. However, it is difficult for operators of different sizes to position the steering column in manner which is both comfortable and which does not obstruct the view.
The prior art illustrates these and additional difficulties. U.S. Pat. No. 4,733,745 discloses an adjustable control attachment for an earth moving vehicle. The steering column is capable of rotation around the base. The drawback to this design is that a smaller individual would need to move the operator's seat rearward, this would move the operator away from any floor pedals. Additionally, the lower portion of the steering column may obstruct the operator's view.
U.S. Pat. No. 4,993,279 discloses a tilt steering column latch release. This column again has a single pivot axis, but also possesses a release mechanism to allow the steering column to move to a lower position to allow easy maintenance.
U.S. Pat. No. 5,088,342 discloses a pivotable steering wheel mechanism and biasing means. The steering column again possesses a single pivoting point which could limit the operator's range of vision.
U.S. Pat. No. 5,168,768 discloses a tilt steering column assembly. The steering column has a single pivot and is capable of being moved back into the original position after being moved.
U.S. Pat. Nos. 5,035,446 and 4,972,732 disclose tilt-telescope steering column for automobiles. Both devices are designed to be attached to a vertical surface. The steering column can telescope and can tilt. The lower portion of the column is fixed and could obstruct an operator's view.
Consequently, the need exists for a steering column which will provide an unobstructed view of farming operations by being able to move in four directions.