User's Manual

GM085_ENG_rev.docx www.loadsystems.com 3
1. Overview
The anti-two-block switch comprises of
the radio transmitter, battery and switch
mechanism. The switch mounts at the
boom tip. A weight and chain assembly is
attached to the bottom piston rod of the
A2B switch. When the weight assembly is
lifted by the ball/block, the internal switch
in the A2B will trip an alarm, warning the
operator of a two-block event.
The switch mounting bracket design
allows the switch to rotate in two axes.
The quick slip design of the mounting
bracket allows the switch to easily be
added or removed from the switch
mounting bracket without the need for
tools.
2. Switch Bracket Installation
LB011
Position the sensor mounting bracket. To
ensure that the sensor can pivot securely
on the mounting bracket throughout the
full range of boom angle, the mounting
bracket must be positioned at a 30° from
horizontal with the boom parallel to the
ground and such that the locking pin of
the mounting bracket points up. Bolt or
weld securely.
Figure 1: Bracket footprint and orientation, all
dimensions in inches, not to scale
Figure 2: Anti-two-block switch placement on a
telescopic boom
If the head sheave diameter is between 8
and 16 inches (20-41 centimetres) then
two mounting brackets will be required to
permit both live and dead end mounting.
Figure 3: Anti-two-block switch placement for live end
mounting on a latice boom
Figure 4: Anti-two-block switch placement for dead
end mounting on a lattice boom
For live end mounting on multiple sheave
blocks with sheaves greater than 16
inches (41 centimetres) in diameter
consult your service representative.
WARNING! Keep the anti-two-
block switch away from the boom
and any connecting metal
structures when welding mounting
brackets to the boom. Proximity to
welding may cause permanent
damage to the anti-two-block
switch and render the anti-two-
block system unsafe.