shoot bolts. An A-Frame folding cylinder is attached to the lower A-Frame transverse beam and
to each outer A-Frame leg.
Extension of the cylinders rotates the outer A-Frame legs from their stowed position about
their upper and lower hinge points. When fully deployed, counterbalance valves hold the A-Frame
folding cylinders in this position until the outer A-Frame legs are pinned securely in position.
To allow the launching vehicle to be leveled laterally on the bridge build site a hydraulic
cylinder is incorporated within the outer A-Frame leg. The cylinder is attached to the outer leg and
to an inner sliding stabilizer leg. Once both stabilizer cylinders have been extended and the
ground bearing pads are in contact with the ground, only the stabilizer on the low side of the
vehicle needs to be further extended to level the vehicle. A level is incorporated on the lower A-
Frame transverse beam to indicate when the vehicle is level. Once level counterbalance valves
hold the stabilizer cylinders in their respective positions until the stabilizer legs are pinned
securely in position.
An A-Frame raise hydraulic cylinder is attached to the upper sliding section of each outer
leg and supports and moves the upper A-Frame transverse beam for bridging module
deployment. Counterbalance valves hold the raise cylinders in the raised position until the upper
A-Frame transverse beam is pinned securely in position.
Two articulating cylinders are connected to the launch beam drive pivot pin and the
articulating cylinder cross member. They are used to articulate the launch beam to accommodate
varying bank heights and to lower the far bank support to the ground once the launch beam is
fully deployed. To allow bridge build to continue the articulating cylinders have to be detached
from the cross member and raised. To facilitate stowing of the articulating cylinders a stowing
cylinder is used. When retracted they rotate the articulating cylinders clear of the bridge surface
1-10-13 Hydraulic Controls
The hydraulic operation of the A-Frame is controlled from two locations on the vehicle. The
A-Frame fold and rotate functions are operated from the interface cabinet located above the tool
chest on the side of the launching vehicle. The A-Frame fold pushbutton is pressed first and its
associated light will indicate when the operation is complete. The A-Frame rotate function is
operated in a similar manner but can not be commenced until the A-Frame fold sequence is
complete. Limit switches are incorporated into the circuit to guard against incorrect sequencing of
The A-Frame stabilizer legs are operated by two manual levers mounted on the rear face
of the lower A-Frame transverse beam. The levers have a spring loaded central `off' position and
must be manually held against the spring in the appropriate direction for the required function to
Once the launcher has been deployed, hydraulic control is carried out via the launch chest
pack. Should electrical failure occur all cylinders and motors can be operated manually.
The A-Frame raise/lower control is an electro-proportional valve mounted on the stabilizer
leg and weighs 44 lb. (20 kg). It is a two-`slice' valve similar to the above and can be operated