Exmark ULTRA VAC LAZER Z HP Operator's Manual page 14

Operation
ramp angle. The trailer or truck should be as level
as possible.
Important: Do Not attempt to turn the unit
while on the ramp, you may lose control and
drive off the side.
Avoid sudden acceleration when driving up a ramp
and sudden deceleration when backing down a ramp.
Both maneuvers can cause the unit to tip backward.
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