Safety Features - freightliner WALK-IN VAN CHASSIS Operator's Manual

by the engine. This results in fuel savings and
less engine wear.
•
Lower highway speed promotes greater fuel
economy.
•
Follow the vehicle maintenance schedule to
keep the vehicle in good working condition.
•
Maintain proper tire pressure. Refer to the tire
manufacturer for correct tire pressure.

Safety Features

The hydraulic hybrid has built-in safety features to
prevent personal injury or component damage in the
event of system pressure leaks or electrical failure.
Brake Energy Recovery Bypass
Brake energy recovery is disabled and the vehicle's
air brakes are enabled to allow normal friction brak-
ing when any of the following conditions occur:
•
The ignition switch is in the OFF position or
there is a loss of electrical power to the HCM
and/or TCM.
•
The vehicle's speed is less than 2 mph (3 km/
h).
•
The accumulator reaches the maximum state-
of-charge.
•
The brake pedal is pressed greater than 65%.
•
There is an antilock brake system (ABS) event.
•
ABS communication is lost.
•
There is not enough regenerative torque to ac-
commodate the driver's torque request be-
cause of system limits such as pump tempera-
tures, pump pressure, etc.
•
There is a fault in the hydraulic hybrid system.
High Pressure Safety Devices
The accumulator velocity fuse (poppet valve) is lo-
cated on the high-pressure fluid side of the accumu-
lator. See Fig. 16.17. The fuse is set to block fluid
flow from the accumulator in the event of a major
leak anywhere in the high-pressure side of the accu-
mulator. The velocity fuse (poppet valve) closes
when the flow rate exceeds 125 gpm (473 L/min),
sealing the opening to prevent further loss of high-
Hydraulic Hybrid
pressure fluid and trapping any remaining fluid in the
accumulator.
4
3
2
1
04/14/2011
1. High-Pressure Fluid
2. Velocity Fuse (poppet valve)
3. Bladder (contains high-pressure nitrogen)
4. High Strength Composite Shell
5. Thermal Relief Valve
6. Gas Fill Valve
Fig. 16.17, Accumulator Safety Devices
A valve block on the nitrogen side of the accumulator
houses a thermal valve that opens to relieve the ni-
trogen gas charge if the ambient temperature
reaches 219°F (104°C). See
prevents a rupture of the accumulator from rapidly
expanding gas in the event of a fire in the cradle.
Manual Bleed-Down Valve
The manual bleed-down valve is located under the
service panel in the floor of the cargo area. A hissing
noise can be heard when the valve is opened, and
high-pressure fluid is redirected back to the low pres-
sure reservoir (LPR). Follow the steps below to ac-
cess and operate the manual bleed-down valve.
1. Park the vehicle on a level surface, shift the
transmission to neutral (N), shut down the en-
gine, and set the parking brake.
2.
Using a flat-blade screwdriver, remove the four
screws that attach the service panel cover to the
cargo floor. See Fig.
3. Use the screwdriver to pry the panel open and
remove it, as shown in
4. To open the manual bleed-down valve, push in
on the knurled knob, then turn the knob counter-
clockwise and release it. See
Fig. 16.21.
5
6
f261422
Fig. 16.17. This feature
16.18.
Fig. 16.19.
Fig. 16.20 and
16.18