General Description
The HYDRA-MATION System is an all hydraulic system that provides automatic control of the elevation of the mainframe and cutter. Pressurized hydraulic oil from the auxiliary pump is directed to a hydraulic cylinder, actuating the cylinder and causing an adjustment of elevation of the mainframe. 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 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 optional cross slope sensor is mounted inside the control console.
When the machine is performing a cutting operation, the front track and, normally, the right rear track travel on uncut grade that may be very uneven. In order to assure that the cut grade is even, the front elevation cylinder is controlled by an elevation sensor and the right rear elevation cylinder is controlled by an elevation sensor or by the optional cross slope sensor. The left rear elevation cylinder remains in a fixed position so that the left rear corner of the mainframe remains at a fixed distance above the cut grade (locked to grade).
On machines with right or left leg slope control, the cross slope sensor may be used to control the left rear leg while the right rear leg is locked to grade.
NOTE: IN ORDER TO ENSURE AN ACCURATE AND TRUE CUT WHEN CROSS SLOPE CONTROL IS TRANSFERRED TO THE LEFT REAR LEG, THE GRADE THE RIGHT REAR LEG RIDES ON MUST BE ACCURATE AND TRUE.
PR-450 ELEVATION CONTROL HYDRAULIC SYSTEM
The elevation sensors must have an external reference in order to control the mainframe elevation.
- 1. A wheel elevation reference assembly mounted on the cutter housing. A caster mount bracket, with a caster wheel at the bottom and a reference rod at the top, rides up and down in two link bars that are connected to a bracket mounted on the cutter housing. Since the caster wheel rides on the uncut grade, irregularities in the uncut grade will be reproduced in the cut grade. This arrangement positions the elevation reference rod near the centerline of the cutter, the best position for controlling the cutter elevation
- 2. A wheel elevation reference assembly mounted on the mainframe forward of the cutter. The same assembly as used in the first arrangement is mounted on a support that fits into a bracket on the mainframe. This arrangement positions the elevation reference rod just forward of the cutter, not as desirable as a position on the cutter centerline, but the reference assembly is moved inboard of the mainframe making it possible to cut near an obstruction such as a curb.
- 3. Averaging ski (optional) - the averaging ski is a beam that mounts to the leg yoke at the rear and rides on caster wheels at the front. The ski is free to ride up and down around the shaft that attaches the ski to the leg yoke. The reference for the sensor is a rod that extends out from the ski. The caster wheels ride on uncut grade, but the length of the ski provides an "averaging" of grade irregularities which makes the cut grade smoother than the uncut grade.
- 2. A wheel elevation reference assembly mounted on the mainframe forward of the cutter. The same assembly as used in the first arrangement is mounted on a support that fits into a bracket on the mainframe. This arrangement positions the elevation reference rod just forward of the cutter, not as desirable as a position on the cutter centerline, but the reference assembly is moved inboard of the mainframe making it possible to cut near an obstruction such as a curb.
Automatic Elevation Control Modes
Depending on the options each machine is equipped with, the PR-450 has up to three automatic elevation modes. Machines without optional cross slope or right/left slope control can use the front and right rear automatic mode selectors in the control console to select mode 1 only. Machines with an optional cross slope are able to select either mode 1 or mode 2 by using the automatic mode selectors. Machines with optional right/left slope control can select any of the three modes by using the automatic mode selectors and the slope control selectors.
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WHEN USING RIGHT/LEFT SLOPE CONTROL, BE SURE ALL FOUR SLOPE CONTROL SELECTOR VALVES POINT IN THE SAME DIRECTION, OTHERWISE ERRATIC MACHINE RESPONSE MAY OCCUR. |
Mode 1 - All machines.
Rear elevation automatic mode selector at "Right Sensor".
Front elevation automatic mode selector at "Left Sensor".
Slope control selectors pointed toward the right (machines with right/left slope control only).
The front and right rear elevation cylinders are controlled by elevation sensors which can be mounted to operate from single wheel elevation reference assemblies or from optional averaging skis. The left rear elevation cylinder is locked to grade.
The depth of cut will be held constant at either edge of the cut grade where a single 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.
Mode 2 - Machines with optional cross slope sensor.
Rear elevation automatic mode selector at "Cross Slope".
Front elevation automatic mode selector at "Left Sensor".
Slope control selectors pointed toward the right (machines with right/left slope control only).
This mode is the same as mode 1 except the right rear elevation cylinder is controlled by the optional cross slope sensor. The right side elevation sensor is not used.
If operating from the single 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 3 - Machines with optional right/left slope control.
Rear elevation automatic mode selector at "Cross Slope".
Front elevation automatic mode selector at "Right Sensor".
Slope control selectors pointed toward the left.
The front elevation cylinder is controlled by the right side elevation sensor which can be mounted to operate from a single wheel elevation reference assembly or from an optional averaging ski. The left rear elevation cylinder is controlled by the optional cross slope sensor. The left side elevation sensor is not used.
If operating from the single wheel elevation reference assembly, the depth of cut at the right 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 right edge of the cut grade that averages the original grade irregularities.
NOTE: WHEN CROSS SLOPE CONTROL IS TRANSFERRED TO THE LEFT REAR LEG, THE RIGHT REAR LEG IS LOCKED TO GRADE. TO PROVIDE AN ACCURATE AND TRUE CUT, THE GRADE THE RIGHT REAR LEG RIDES ON MUST BE ACCURATE AND TRUE.