All Motion Alarm; Gradeability; Theoretical Gradeability; Actual Gradeability - Snorkel AB46JE Operator's Manual

Chapter 9 – Operation
• When either boom is elevated or extended, only the
slowest drive speed will work regardless of the drive
range switch position.
• To avoid a sudden speed change from high to low
boom speed, always bring the machine to a stop be-
fore raising the booms from the stowed position.
A
Warning
The potential for an accident increases when safety
devices do not function properly. Death or serious
injury could result from such accidents. Do not alter,
disable, or override any safety device.
Do not use the aerial platform if it drives faster than 0.8
miles per hour (50 feet in 42.5 seconds) when any of the
booms are out of the stowed position.

All Motion Alarm

The optional all motion alarm sounds loud intermittent
beeps anytime the machine functions are being oper-
ated.

Gradeability

Gradeability refers to the maximum slope that the aerial
platform is capable of travel. Gradeability can be de-
scribed as "theoretical" or "actual" with the slope, or grade,
measured in percent of slope or degree of slope.

Theoretical Gradeability

Theoretical machine gradeability refers to the maximum
slope that the machine is capable of travel under perfect,
or theoretical, conditions. It is based on mathematical
calculation, not practical application.
Some of the factors taken into consideration when cal-
culating theoretical gradeability include:
• Drive motor effi ciency
• Machine weight
• Machine center of gravity
• Tire traction
• Tire contact
• Condition of slope
The value for theoretical gradeability will most always be
high when compared to the actual gradeability value. The
perception then is that the machine can climb a steeper
slope than is actually practical.

Actual Gradeability

Actual machine gradeability refers to the maximum slope
that the machine is capable of travel under practical condi-
tions. It, too, is based on mathematical calculation, but it
also takes into account the practical application.
At any given moment when driving the machine on a
slope, at least one, if not all, of the factors contributing
to achieving theoretical gradeabilty will not be at optimal
performance. For example, tire contact may not be the
42
same at each drive wheel or the slope conditions may not
be optimal, which would then allow for loss of traction.
The value for actual gradeability will always be lower
than the theoretical gradeability value. The perception
then is that the machine can not climb a slope as steep
as it should.

Percent vs. Degree of Slope

Gradeability is most often referenced as a percentage.
That value is based on a slope angle of 45° representing
100% grade.
Angle indicators, or inclinometers, often measure the
angle of the slope in degrees not the percent slope.
Because of that, it may be useful to understand the re-
lationship between percent slope and the degree of the
slope angle as shown in Figure 9.4.

Driving on a Slope

The machine should only be driven on a slope or load-
ing ramp in the stowed position with the platform on the
downhill side.
A
Danger
The aerial platform can tip over if it becomes
unstable. Death or serious injury will result from a
tip-over accident. Do not drive on slopes that exceed
25 percent grade, or where conditions of the slope
could cause driving to be hazardous.
Place the drive range switch in the low position before
attempting to drive the machine on a slope.
Drive the aerial platform only on slopes, or loading ramps
that are within the 25 percent grade capability of the
aerial platform.
Calculate the percent grade:
• before attempting to climb an unknown grade.
• if it is believed that there is a malfunction to determine
if the slope is within the actual grade capability of the
aerial platform.

Calculating Percent Grade

The percent grade equals the height (rise) of the slope di-
vided by the length (run) times 100. Refer to Figure 9.5.
AB46JE – 0260072