Workhorse has found that motorhome drivers often overheat and damage
their vehicle braking systems by improper braking in mountain areas or
by “riding” the brakes on flat ground. The following includes
suggestions from the Workhorse Technical Team as well as recommendations
outlined in the DOT (Department of Transportation) commercial driver’s
license manual. Workhorse has included these DOT procedures in its
owner’s manuals since 2007 and they apply to all types of motorhomes.
In mountain driving, gravity plays a major role. On any upgrade,
gravity slows you down. The steeper the grade, the longer the grade,
and/or the heavier the load – the more you will have to use lower gears
to climb hills or mountains. In coming down long, steep downgrades,
gravity causes the speed of your vehicle to increase. You must select an
appropriate safe speed, and then use a low gear and proper braking
techniques.
You should plan ahead and obtain information about any long, steep
grades along your planned route of travel. If possible, talk to other
motorhome or truck drivers who are familiar with the grades to find out
what speeds are safe. You must utilize engine braking techniques to go
slow enough so your brakes can be utilized for speed reduction without
getting too hot. If the brakes become too hot, they may start to “fade.”
This means you have to apply them harder and harder to get the same
stopping power. If you continue to use the brakes hard, they can keep
fading until you cannot slow down or stop at all.
Select a safe speed
Your most important consideration is to select a speed that is not too fast for the:
– Total vehicle and cargo weight
– Length of grade
– Steepness of grade
– Road conditions
– Weather
If a speed limit is posted, or there is a sign indicating “Maximum
Safe Speed,” never exceed the speed shown. Also, look for and heed
warning signs indicating the length and steepness of the grade.
You must use the braking effect of the engine as the principal way
of controlling your speed. The braking effect of the engine is greatest
when it is near the governed rpms and the transmission is in the lower
gears. Save your brakes so you will be able to slow or stop as required
by road and traffic conditions.
Choose the right gear before starting down the grade
Shift the transmission to a low gear before starting down the
grade. Pay close attention to the gear that is required to climb the
grade prior to descent. For example, if the gear required to climb the
grade is third gear, then third gear should be selected prior to the
descent as a base line to control your motorhome’s speed. Do not try to
downshift after your speed has already built up above the safe posted
speed limit. Once your speed has increased over the safe posted speed
limit you may not be able to shift into a lower gear. You may not even
be able to get back into any gear and all engine braking effect will be
lost.
With motorhomes, a rule for choosing gears has been to use the same
gear going down a hill that you would to climb the hill. However, new
motorhomes have low friction parts and streamlined shapes for fuel
economy. They may also have more powerful engines. This means they can
go up hills in higher gears and have less friction and air drag to hold
them back going down hills. For this reason, drivers of newer motorhomes
may have to use lower gears going down a hill than would be required to
go up the hill. Usually you want the lowest gear that will keep the
motorhome at or near the speed you want in negotiating the downhill. For
example, if you’re going down a 6-percent grade and want to go 35 mph,
you would start downshifting and using the brakes to get to an engine
rpm that will enable you to maintain a speed at or near 35 mph.
Use proper braking techniques
Remember, the use of brakes on a long and/or steep downgrade is only a supplement to the braking effect of the motorhome’s engine. Once the coach is in the proper low gear, the following is the proper braking technique:
1. When your speed increases to or above your “safe” speed,
apply the brakes aggressively enough to feel a definite slowdown.
2. When your speed has been reduced to approximately 5 mph
below your safe speed, release the brakes. (This brake application
should last for about three seconds.)
3. When your speed increases again to your safe speed, repeat steps 1 and 2.
For example, if your safe speed is 40 mph, you would not apply the
brakes to any increase in speed until you reach 40 mph. Then you apply
the brakes aggressively enough to gradually reduce your speed to 35 mph
and then release the brakes. Repeat this as often as necessary until you
have reached the end of the downgrade.
Avoid brake fade or failure
Your brakes by design operate utilizing brake pads that rub against
the brake disks to slow the motorhome during brake application. This
braking function creates heat, which the brake system can dissipate
during normal brake applications. However, brakes can fade or fail from
excessive heat caused by improper use or dragging the brake to slow the
vehicle on mountain grades rather than relying on the engine braking
effect. To safely control a vehicle, every braking mechanism must do its
share of the work. Brakes with excessively worn pads or rotors will not
provide the same degree of braking power. If you are not sure about the
condition of your braking system, have it inspected at a qualified
service center.
Escape ramps or runaway truck ramps
Escape ramps, also known as Runaway Truck Ramps, have been built on
many steep mountain downgrades. Escape ramps are made to stop runaway
vehicles safely without injuring drivers and passengers. Escape ramps
use a long bed of loose, soft material to slow a runaway vehicle,
sometimes in combination with an upgrade. Know escape ramp locations on
your route. Signs show drivers where ramps are located. Escape ramps
save lives.
Here’s an example of brake-friendly driving technique in Death Valley
On a recent trip to California we made notes on driving technique when descending a mountain pass.
Background:
The motorhome was built on a Workhorse W22 gas chassis, fully laden
to 22,000 lb. GVWR. The driver, let’s call him Mike, is an experienced
driver with a valid Commercial Driver’s License and is also a
professional automotive technician. We asked Mike to drive the vehicle
in a fashion that would conserve the brakes, but also be reasonable in
using the engine and transmission for braking (i.e. drive it like you
own it!).
We were traveling in a south-westerly direction into Death Valley
National Park from the Nevada side on SR-374, with a planned stop at
Stovepipe Wells Village in the park. This is quite a steep descent with
almost 10 miles of 7 percent grade and 4 miles of 5 percent grade, with a
total drop of around 4,000 foot over 12 miles of driving. The speed
limit on some road sections inside the National Park on this road is 45
mph, so Mike shifted down to second gear as soon as we hit the
down-grade. The motorhome was a 2005 model with the five-speed Allison
transmission and equipped with the “Grade-Brake” feature, but Mike
elected not to use the Grade Brake, instead preferring to manually shift
down using the column shift.
Mike would allow the vehicle to run against engine compression with
the engine speed varying between 4,000 rpm to 5,200 rpm, depending on
the grade. Each time we hit 5,200 rpm the transmission would force a
shift into third in order to protect the engine. Each time this happened
Mike applied the brake for a few seconds to scrub off speed and this
allowed the transmission to downshift to second gear again, allowing
maximum engine braking in the safe speed range. Drivers should not be
concerned about the high rpms in this situation because, as noted, the
transmission will automatically adjust when needed to protect the
engine. Also, if Mike had elected to use the Grade Brake feature, the
down- and up-shifting would have happened automatically once he touched
the brake pedal.
Overall, Mike applied the brake only seven times during the 14-mile
descent and this includes the final stop at the T-junction with the
North Highway! Most of the applications were of short duration, with
less than 5 seconds of brake pedal application required to control the
vehicle speed.
