General
The HYDRA-MATION System is an all hydraulic system that controls machine elevation, either manually or automatically, and machine steering, manually only. Pressurized hydraulic oil from the auxiliary pump is directed to a hydraulic cylinder, actuating the cylinder and causing an adjustment in elevation or travel direction. The flow of hydraulic oil to the cylinders is regulated by hand operated valves (manual control) or hydraulic sensors (automatic control). The hand operated valves are all located in the control console with the function of each valve clearly marked. An elevation sensor is mounted on each side of the machine and the cross slope sensor is mounted by the fuel tank.
The auxiliary pump is an axial piston, variable displacement pump similar in operation to the wheel and cutter pumps. However, the auxiliary pump is a pressure compensated pump; the output of the pump is controlled by a pressure compensator that automatically changes the pump swash plate angle to vary the amount of fluid flow and thus maintain a constant system pressure.
When the machine is performing a cutting operation the left front wheel and right wheels travel on uncut grade that may be very uneven, and the left rear wheel travels on the cut grade. In order to assure that the cut grade is even, the left front elevation cylinder is always controlled by an elevation sensor and the right elevation cylinders are controlled by an elevation sensor or the cross slope sensor, whenever automatic elevation control is used. Since the left rear wheel travels on the cut grade, there is no requirement for automatic elevation control and the elevation cylinder remains in a fixed position. The left rear corner of the mainframe therefore remains at a fixed distance above the cut grade (locked to grade).
The elevation sensors must have an external reference in order to control the mainframe elevation.
- 1. Single wheel elevation reference assembly - a square support rod with a wheel at the bottom and a reference rod at the top, rides up and down in a support that is connected to the cutter assembly. Since the wheel rides on the uncut grade, irregularities in the uncut grade will be reproduced in the cut grade. If the wheel rolls into a chuck hole, the cutter will drop a corresponding amount.
This arrangement will not remove any irregularities in the surface.
- 2. Dual-wheel elevation reference assembly - this is essentially the same as the single wheel elevation reference assembly, except that an aluminum channel with two wheels is attached to the bottom of the support by use of an adapter. The attachment of the channel to the support allows one wheel to drop into a hole while the other wheel rolls on the grade. Some of the irregularities in the uncut grade will therefore be reduced in the cut grade.
This arrangement will reduce any irregularities in the surface by a small amount.
- 3. Averaging ski - the averaging ski assembly consists of a ski at the front of the machine, a ski at the rear of the machine and a stringline run between the skis. The skis ride on small wheels and are free to pivot up and down around the pins which connect the skis to the mainframe. The reference for the elevation sensor is the stringline. The wheels of the ski ride on uncut grade, but the length of the ski assembly provides an "averaging" of grade irregularities which makes the cut grade smoother than the original grade.
This arrangement will reduce any surface irregularities by a relatively large amount.
- 2. Dual-wheel elevation reference assembly - this is essentially the same as the single wheel elevation reference assembly, except that an aluminum channel with two wheels is attached to the bottom of the support by use of an adapter. The attachment of the channel to the support allows one wheel to drop into a hole while the other wheel rolls on the grade. Some of the irregularities in the uncut grade will therefore be reduced in the cut grade.
Manual elevation control is accomplished with the elevation control levers. The steering wheel is used to manually steer the machine.
Automatic Elevation Control Modes
There are two possible modes of automatic elevation control. The mode is selected by placing the right elevation automatic mode selector lever at "Cross Slope" or "Sensor".
Mode 1
Right side elevation automatic mode selector at "Cross Slope"
The left front elevation cylinder is controlled by an elevation sensor which can be mounted to operate from a single or dual wheel elevation reference assembly, or from an averaging ski assembly. The cross slope sensor controls the right side elevation cylinders. The left rear elevation cylinder is locked to grade.
If operating from the single or dual wheel elevation reference assembly, the depth of cut at the left edge of the cut grade and the cross slope of the cut grade will be held constant. An averaging ski will provide a depth of cut at the left edge of the cut grade that averages the original grade irregularities.
Mode 2
Right side elevation automatic mode selector at "Sensor".
This mode is the same as mode 1 except that the right side elevation cylinders are controlled by an elevation sensor operating from a single or dual wheel elevation reference assembly, or from an averaging ski. The cross slope sensor is not used.
The depth of cut will be held constant at either edge of the cut grade where a wheel elevation reference assembly is used. An averaging ski used on either side will provide a depth of cut at that edge of the cut grade that averages the original grade irregularities.