www.energyabsorption.com
Revision B December 2013
www.highwayguardrail.com
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Operation Instructions
The Alpha Truck Mounted Attenuator (TMA), Model TMA 7590 has been equipped with a
hydraulic pump which can be used to tilt the energy absorbing Cartridge from its horizontal
position as well as remotely latch it in the vertical position. The “tilting” feature may be used to
prevent possible scraping of the rear end of the Cartridge as the truck travels in and out of
sloped driveways. The driver simply activates the “UP” button from inside the cab to
momentarily tilt the Cartridge up. When he removes his finger from the button, it will slowly
bleed back down to its horizontal position.
The hydraulic system can also be used to tilt the Cartridge to a full 90 degree “UP” position
where it will stay locked. This feature allows the TMA equipped truck to be easily driven and
parked in congested areas. It should be remembered that for the TMA to function properly
during a crash, the Cartridge must be in the horizontal, “DOWN” position. To lower the Cartridge
from the 90 degree “UP” position, the driver must exit the cab and check behind the Cartridge to
make sure everything is clear.
A full set of procedures to operate the system follows:
Raise and Lower 90 Degree Tilt Systems
1. RAISE the Cartridge:
A. Make sure the top of the Cartridge is clear of all objects before proceeding.
B. Activate the hydraulic system to raise the Cartridge using the switch in the cab or the
switch located on the side of the Support Frame.
C. The Cartridge may be tilted a full 90 degrees where it will be locked in the up position, or
it may be tilted approximately 30 degrees to travel up sloped driveways, after which it will
bleed back down to the horizontal position.
D. To lock the Cartridge in the full up position, keep the activation switch “ON” for five (5)
seconds after the Cartridge reaches the full up position (this allows enough time for the
sequence valve to activate the locking pins).
Danger:
Under no circumstances should anyone be allowed behind an
elevated Cartridge when the latch pins are not fully seated in their locked
position.
2.
LOWER
the Cartridge from full 90 degree position:
A. Activate the down switch to release the latch pins (this is to be accomplished from the
rear corner of the truck so that the operator can check to make sure everyone is clear).
Release the DOWN switch and the Cartridge will lower to the horizontal position.
Danger:
As Cartridge starts to lower, stand clear of moving parts.
B. Cartridge will then “bleed-down” in 15 – 30 seconds, regulated by the flow control valve
attached to the cylinder.
C. The external switch and cord should be properly stored before moving the truck.
