University Forum: Answers To GU Students' Questions
Q. The front of one of the tracks on my two-track paver keeps coming off the ground. What could be causing this and how do I correct it?
A. The machine frame is rigid, especially when paving a narrow width. It is recommended that after the machine frame has been set parallel to the guideline, it should be checked for maximum flex. Start the engine and place all elevation controls in the automatic mode. Slowly raise the left front corner of the machine by turning the grade jack, until the rear of the left track, or the front of the right track, begins to come off the ground. Lower the left front corner, counting the number of turns of the grade jack, until the front of the left track begins to come off the ground. Raise the left front corner half the number of turns. This will place the frame in the "relaxed" position so that the frame can flex the maximum amount in either direction when a grade correction is called for, before a track comes off the ground.
NOTE: The test can be performed on any corner. It is advisable to leave the outer frame clamps loose when paving in the minimum width mode, to allow more frame flex.
Q. How do I adjust the adjustable drum on my double drum C-450?
A. After the carriage rail has been properly adjusted, the bottom of the drums must be stringlined to final grade. Stringline the bottom edge of the drums to the slab forms, which determine the final grade. The forms must be set to proper grade throughout the length of the slab before the drums can be set correctly. Loosen the adjustable drum locking nuts on the front and rear of the undercarriage and turn the front and rear adjusting nuts to raise the adjustable drum as high as it will go. Securely tighten the two locking nuts. Move the carriage to the console end of the machine. Move the machine forward or backward until the back of the fixed drum is over the stringline. Check the distance between the bottom of the finishing drum and the stringline. Remove the 3/8 inch locking pin and adjust the rear grade jack on the console end up or down until the rear of the finishing drum just touches the stringline. Replace the jack locking pin. Move the machine backwards until the front of the finishing drum is directly over the stringline. Check the distance between the bottom of the finishing drum and the stringline. Remove the 3/8 inch locking pin and adjust the front grade jack up or down until the front of the finishing drum just touches the stringline. Replace the jack locking pin. Move the carriage to the idler end of the machine and repeat the entire procedure to adjust the machine on the idler end.
Return the carriage to the console side of the frame and move the machine forward or backward to position the rear of the adjustable drum directly over the stringline. Loosen the rear adjustable drum locking nut and turn the adjusting nut to lower the adjustable drum until it just touches the stringline (the front of the adjustable drum may have to be lowered part way first). Securely tighten the locking nut. When the rear of the adjustable drum is set to the stringline, back up the machine until the front of the adjustable drum is directly over the stringline. Loosen the front locking nut and adjust the drum to the stringline. Move the machine forward again and recheck the rear of the adjustable drum. Readjust as necessary. Move the carriage to the idler end of the machine and recheck the alignment of the adjustable drum. Readjust and repeat the procedure as necessary.
NOTE: If the adjustable drum is not set correctly according to the directions above, each drum will cut the concrete to a different grade when the carriage moves left and right across the slab.
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