Terex Series AL4000, Руководство по эксплуатации и обслуживанию

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CRITERIA FOR REPLACEMENT OF WIRE ROPE – TEREX-AMIDA LIGHT TOWERS
The wire ropes used to raise and lower the masts on a TEREX-Amida Light Tower are probably some of the most
important mechanical parts used in day-to-day operation of the machinery. It is therefore very important that the cables be
inspected on a frequent basis (once a month) for wear and tear, and immediately in the event of possible damage due to
operator error in using the winch, or possible damage from other equipment.
NORMAL WEAR AND TEAR
When used properly, the wire ropes should give years of trouble-free service, depending on how often the masts are
raised and lowered. The rule of thumb at TEREX-Amida is that if the tower is
raised and lowered an average of once
per day , that the cables should be replaced every two years of service .
NORMAL INSPECTION
The wire ropes are constructed of 7 strands of 19 plow steel wires each twisted together, and then the assembly galva-
nized to resist corrosion. Using a wadded-up cloth or heavy leather gloves (to avoid being pricked by a broken wire), run
a hand up and down a length of the cable. If any exterior wires are broken, they will lift up from main body of the cable
and become visible. For any given 1 foot of cable length; if there are 4 or more wires each, on any 2 or more strands
broken, the suspect rope
should be replaced immediately .
OPERATOR ERROR – OTHER MACHINERY DAMAGE
One of the most common reasons for failure of a Light Tower wire rope is due to operator error in using the winch, or
damage to the cable by tools or other machinery. The most common operator error happens when the mast is telescoping
down.
When the upper telescoping lock engages, the operator does not pull the lower pivot lock out (located on the
tower base) and keeps on cranking the winch. This results in the cable becoming loose around the drum due to the
tower not pivoting down
. This can result in three problems: the loose cable can get trapped underneath itself, resulting
in a sudden or partial “drop” of the mast when the loose section releases at a later time, thus damaging the cable; or the
cable can jump off the winch drum and be damaged by the gears of the winch. The loose cable can also cause the drum to
spin to take up the slack cable. If there is enough friction in the threaded parts of the winch, the drum can cause the crank
handle to start spinning. This can cause the tower to “freefall” and the results can be catastrophic for anyone standing
underneath the tower. A spinning crank handle can also break bones.Other reasons damage can occur are due to some
outside force such as forklift blade nicking or crushing a cable when moving a unit, or an accidental blow or damage by a
hand tool, etc.
DAMAGE INSPECTION
If any nicks (partial strand cut through), kinks (permanent bends), or weld spatter on the cable (from field service) are
observed, the suspect wire rope
should be changed immediately.
If there is a crushed spot somewhere on the wire rope, it should be replaced only if the width of the crushed spot exceeds
1-1/4 times the nominal diameter of the cable (5/16” on a 1/4” cable, and 7/32” on a 3/16” cable), or if there are broken
wires at the point of damage.
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