HEATER & AIR CONDITIONER AR 4508715 - Caterpillar

A template and large calipers used as a gauge aid in restoring rollers and idlers to original dimensions.Note: The true center line must be kept on all idler rebuild procedures. All idler width dimensions are based off center line of the idler. Measure from machined retainer surface on hub to establish the true center line of hub.A stepover of 1/3 to 1/2 the bead width every revolution finishes with a smooth surface.When the roller flanges are hard surfaced, the roller axis may be positioned 5 degrees to 45 degrees from the horizontal.
Illustration 8 g02353420
Roller flange build-up
(3) Welding head
(4) RollerMove the head 4.233 mm (1/16 inch) to 3.175 mm (1/8 inch) further off center from the position used for building up the tread area as shown in Illustration 8.
Illustration 9 g02353421
Idler edge beads
(14) Improper bead
(15) Proper edge bead
Illustration 10 g02353422
Idler edge bead build-up
(16) Idler flange
(17) Build up on edge firstRebuilding the edge of the idler to size by laying successive beads one on top the other before stepping over is an advantage. It is difficult to hold the molten metal and flux on the edge if the idler is too hot from welding the tread area. Refer to Illustration 8 and Illustration 9.Welding should be started at the edge of the idler and continue into the base of the flange.When the idler flanges are hard-surfaced, the idler can be placed either in a horizontal position or tilted 20 degrees from the vertical. The surface of the idler acts as a flux support when placed in these positions.Note: The true center line must be kept on all idler rebuild procedures. All idler width dimensions are based off center line of the idler. Measure from machined retainer surface on hub to establish the true center line of hub.Travel Speed
Travel speed affects the penetration and bead width. If the travel speed is doubled, the penetration and bead width is reduced to about half. Penetration is reduced because the same amount of wire is spread over a greater length of work.Lead
Illustration 11 g02353423
Correct lead will give the proper bead
(A) Approx. 25.4 mm (1.00 inch) for 203 mm to 228 mm (8 inch to 9 inch)
(2) Flux feed tube
(6) Proper beadNote: First bead on roller will be oval or convex at proper distance setting.Lead plays an important part in submerged arc welding on cylindrical work and compares closely with rod position in manual welding. On cylindrical work, the arc is about 1 inch ahead of top center to give the molten flux an opportunity to form the desired bead. The one basic requirement is that the molten metal must at least partially solidify before the molten metal passes top center. Refer to Illustration 11.Lead is an adjustment that must be understood by an operator. Voltage, current, or travel speed adjustments should not be used to overcome a faulty lead adjustment. Bead shape will demonstrate to the operator whether the lead is correct or not.
Illustration 12 g02353424
Too far off center
(18) Bead high oval
(19) Bead irregular along edge
(20) Bead flat-may hair