Road grinding machines?

All the road grinders I've ever seen have had a 5-6' track at about 3 places under them, 1 fore 2 aft. That would act like a long shoe on a woodworking plane to smooth out any lumps and bridge any holes.

What's that Lassie? You say that snipped-for-privacy@hotmail.com fell down the old rec.crafts.metalworking mine and will die if we don't mount a rescue by Mon, 14 Sep 2009 13:55:10 -0600:

Same as a road grader. Support for and aft on wheels or tracks, and cutter head in between. Bumps and dips are reduced by half due to the position of the support relative to the cutting area.

Think of a flat road with a speed bump on it. As the grinder approaches and the front wheels rides up on the bump the whole machine tilts back. The rear wheels stay on the flat part of the road. The cutter is lifted up, but not as much as the front wheels, leaving a high spot. As the machine continues, the cutter head grinds down the bump. Then the rear wheels encounter the high spot that the cutter left, and the whole machine tilts forward as the rear wheels go over the high spot. This lifts the cutter head again, but to a much smaller degree. Further passes continue to reduce the high spots.

Problems can occur if the bumps are at the same spacing as the wheelbase of the machine. It helps to have the cutter head closer to the rear wheels.

Don't know about grinding machines but a lot of pavers used to use a long, multi section ski to average out the surface - not so critical on urban roads but critical on airport runways. Gerry :-)} London, Canada

Most of the newer computerized ones go one better. They use a tracking system that measures the humps and bumps and tells the computer where they are. The computer then adjusts the cutter to suit. Most of the newer rigs use sonar/laser sensors to track the road profile.

You can see the earlier version of this on the skid style paver machines.