b. Aggregate Stockpile Areas. The remote stockpiling of sand, gravel, and rock is a common dump truck operation,
but it should not be attempted with dump trucks alone. A scoop loader is necessary to keep the dumping area level and
clean for heavy truck dumping. Ruts and humps of spilled aggregates can lead to tip-over problems. Keep the dump
area clean and level.
c. Road and Runway Building Areas. Spreading operations, using heavy dump trucks, on trails, haul roads, and air
strip runways, has factors similar to the lift type fill operations in "a" above. Initially, the first few trucks spreading over
rough surfaces had best do their spreading in reverse gear (if practical) with assistance of the dump site spotter. By
having your heavy dump truck run over and compact its own aggregate lift, a much firmer dumping surface for the
following trucks will provided. The dump truck's speed, rate of dump body spread, and guidance of the spotter must be
coordinated to result in a smoother lift without leaving humps and piles of aggregate, where the truck's motion stopped for
a moment. In spreading trails in hilly terrain, either begin dumping at the top of the hill and bulldoze the payload down hill
or, if the hill isn't over 15%, the driver may be able to spread his payload with the truck facing down-hill. Spreading with
the tailgate downhill could result in a tip-over backwards, especially if the brakes are applied rolling downhill or if the
power is applied climbing uphill.
7.
Dump Truck Working Angles. Very, very few trained people can tell the differences of dump sites having a level to
7% side slope or a level to 6% longitudinal grade. Also, you don't know what weight the soil will bear with the heavy dump
truck's dual rear tandem on it. If one side sinks down, you're in possible trouble from a tip-over. Spotters should pick
dump areas that look the best and that have been compacted firmly. During the dump cycle both the spotter and the
dump truck driver must be observant and look for the first sign of a tip-over. To the spotter, this would be the tell-tail
sideways movement of the top of the cab protector. To the driver, this would be a seat-of-the-pants feeling of the truck
shifting toward the left or the right. The truck driver has control of the rate of dump body hoist. As the dump body leaves
the truck, an engine speed of not more than 1500 RPM is okay, but as the bed get higher, ease up on the accelerator
treadle to 1000 RPM and 800 RPM while the payload slides out of the bed. The dump truck bed will hoist to make angle
of 50 with the frame, however, most of payloads will begin sliding out at 35 angles and should be all out by 40t o
45angles. The spotter should observe when the payload begins to slide and
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