Chain Tension Inspection; Chain Elongation Inspection - Upright TM12 Service Manual

Section 2 - Service and Repair
C
H A I N
Refer to Figure 2-16: "Elevating Assembly," on page 2-19.
The lifting chains are self-adjusting and should always be close to the same tension. This tension should
be checked annually to ensure that there are no problems with this system. To do this task a spring scale
will be needed with 20 kg (44 lb.) capacity.
1. Place 227 kg (500 lbs.) in the platform including the weight of the person testing the chain tension.
2. Remove the chain inspection cover (8) and raise the platform approximately 10 cm (4 in.) until the outer
inspection hole lines up with the inner inspection hole.
3. Attach the spring scale to one of the outer chains and pull until the chain makes contact with the inner
surface of the mast section. Note the scale reading.
4. Repeat Step 3 on the other outer chain.
5. Compare the scale readings. The readings for each chain in the outer set should be within 20% of each
other.
6. Repeat Step 3 through Step 5 for the inner set of chains. The readings for each chain in the inner set
should be within 20% of each other.
IMPORTANT: If the readings are not within 20%, then a problem exists that is causing unequal chain tension.
Investigate the problem and repair or replace the worn components.
C
H A I N
At five-year intervals, the chains
should be removed from the
mast and the entire length of the
chain inspected for excessive
wear and elongation. Follow the
procedure below to disassemble
the elevating assembly. With the
lift chains removed, hang them
vertically from something capable of holding 100 kg (220 lbs.). Inspect the chains thoroughly, looking for
cracks in the chain links, kinks in any portion of chain, and excessive corrosion. Complete the following
elongation test:
1. Attach approximately 25 kg (55 lbs.) to the lower end of each chain.
2. Measure the distance between 50 pins. This distance should be 63,5cm - 65,5cm (25 in. - 25¾ in.).
3. Remove the weight and measure the same on the other three chains.
If the chains have elongated beyond the indicated range, replace the lift chain sets. Before reinstalling the
lift chains, take this opportunity to thoroughly clean and lubricate the entire chain. Reassemble the elevat-
ing assembly as described below.
107099-002 TM12 Work Platform
T I
E N S I O N N S P E C T I O N
E I
L O N G A T I O N N S P E C T I O N
MEASURE DISTANCE OF 50 PITCHES
Elevating Assembly
Figure 2-17: Chain Elongation Inspection
ONE
PITCH
Page 2-21