JLG G12-55A AccuPlace Service Manual - Manual (Page 28)

Boom
3.6 G10-55A & G12-55A AccuPlace
Note: Be certain the hydraulic sub-assembly locks into
place on the pin bracket at the bottom of the fourth boom
section.
4. Reconnect the hydraulic hoses and any optional
circuits.
5. Install the guide bracket and hardware to secure the
hydraulic sub-assembly to the front of the boom.
6. Reinstall the hose take-up compression spring.
Torque the jam nut to 100 lb-ft. There should be a
1 in. (25 mm) gap from the back of the jam nut to the
end of the threads on the hose take-up weldment.
7. Install the wear pads, backing plates and shims to
the top, bottom and sides of the fourth boom section.
Do not shim or tighten the bolts at this time.
8. Attach the chain clevis and the keeper plate to the
inside rear of the boom.
9. Install the grease fitting extensions for the bottom
rear wear pads.
10. Lubricate the extend chain completely. Make sure
the chain is inspected and is in good working
condition. See Section 3.4.4, “Chain Lubrication.”
11. Attach the chain to the chain clevis.
12. Attach the chain clevis to the top of the fourth boom
section.
13. Grease the inside of the third boom section on areas
where the fourth boom section wear pads will slide.
14. Using a suitable sling, balance the fourth boom
section and carefully slide 3-4 ft (1-1,5 m) into the
front of the third boom section. Set the fourth boom
section head onto suitable supports and reset sling
under the boom head. Carefully slide the fourth
boom section into the third boom section. Leave
6-8 in (15-20 cm) of the fourth boom section out to
be able to install wear pads on the front of the third
boom section.
15. With the boom head still supported, install the top
wear pads, washers and bolts in the front of the third
boom section. Remove the boom head from
supports and install the remaining wear pads inside
the third boom section. Do not shim or tighten the
bolts at this time.
16. Install the grease fittings for the wear pad and chain
roller assembly.
3.3.6 Third & Fourth Boom Section
Installation
1. Install the top, bottom and side rear wear pads onto
the third boom section. Do not shim or tighten the
bolts at this time.
2. Grease the inside of the second boom section on
areas where the third section wear pads will slide.
3. Install the grease fittings for the wear pad and chain
roller assembly.
4. Install the chain clevis to the rear of the third boom
section.
5. Install the chain roller (1) at the bottom rear of the
boom.
6. Install the chain roller at the top front of the boom.
7. Lay out and lubricate the retract chain. Make sure
the chain has been inspected and meets the
adjustment parameters in Section 3.4.1, “Boom
Chain Inspection.”
8. Connect the retract chain (2) to the clevis at the rear
of the fourth boom section.
9. Connect the chain to the chain clevis and the clevis
to the chain adjustment block. Adjust the nut until the
gap between the nut and the washer is 1/8 in.
(3,175 mm). Torque the locknut to 100 lb-ft
(135 Nm).
10. Lay out and lubricate the two extend chains. Make
sure the chains have been inspected and meets the
adjustment parameters in Section 3.4.1, “Boom
Chain Inspection.”
11. Attach the rear chain clevis to the chain.
12. Using a suitable sling, balance the fourth and third
boom sections and carefully slide 3-4 ft (1-1,5 m)
into the front of the second boom section. Set the
fourth and third boom sections onto suitable
supports and reset the sling under the boom head.
Carefully slide the fourth and third boom sections
into the second boom section. Leave 6-8 in
(15-20 cm) of the third boom section out to be able to
install the wear pads on the front of the second
section.
13. With the boom still supported, install the top wear
pads in the front of the second boom section.
MX0380
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