How important is it? I had my Cat D3G LGP 2005 serviced by a Cat dealer in April. They indicated the tracks were loose. They were tightened. I have put about 250 hours on the machine since then. I decided to do the full track adjustment process this week-end. According to the O&M manual they were very tight, for matter of fact, there almost was no sag. According to the book the combined sag from the front idler to the carrier roller plus the sag from the carrier roller to the rear sprocket should be 80 mm or about 3 inches. I adjusted the track to a sag of about 50 mm. Wow. Much nicher to maneuver. How could they have gotten it so wrong? I plan to further adjust until I get it closer to the spec of 80 mm. Could this have put stress on the tracks and undercarriage? And did it do unnecessary wear to the undercarriage? Everything seems fine but I am disappointed that I had to learn this the hard way.
I keep the factory specs,... perhaps the mechanic thought a dozer and a crawler loader were the same , they are not. Dozers have grousers,, they need the slack.
I dont like tracks as tight as a banjo string on any machine.I usually like to see 11/2 to 2 inch sag between the top rollers front idler & rear sprocket.
When they are real tight, can that cause damage?
it's a lot of force on the pins, bushings, idler and drive bearing. and it takes power and on certain ground will give you less purchase.
You will learn the way they should look when adjust correctly, certain materials can pack on the bushings and segments which causes the track to tighten if that occurs they should be loosened then once the machine is away from that material tightened back up. I always counted the grease gun strokes while tightening to keep both sides the same. Never used a power gun
On the later machines at least from the books I've seen track droop is used as a guide as to when to adjust. Actual adjustment is supposed to be done by tightening the track until all slack is gone then releasing the adjuster until there is x stroke measurement on the adjuster as it slackens. If the mechanic got carried away with his grease gun he might have gone past the point where the track was tight and collapsed the spring and got a false adjustment. Just a theory. I really like the old way better.
I found this information on John deere's site about how a tight track effects wear: Track tension and track sag affect wear The most important controllable factor in undercarriage wear is correct track-chain adjustment. Correct track sag for all conventional crawlers is two inches (± 1⁄4 inch). Tight tracks can increase wear up to 50 percent. For example, a crawler in the 80-horsepower range with 1⁄2-inch track-chain sag results in approximately 5,600 pounds of chain tension when measured at the track adjuster. The same machine with the suggested 2-inch trackchain sag results in approximately 800 pounds of chain tension when measured at the track adjuster. A tight track magnifies the load, which results in more wear on the track bushings to sprocket teeth contact areas and the track-link-to-idler roller contact areas. Increased wear also occurs at the track-link-to-idler contact point and track-link-to-roller contact points. More load means more wear on the entire undercarriage system. I think tight tracks is a real issue, the whole article can be found at : http://www.deere.com/en_US/cfd/construction/deere_const/media/pdf/DKB765.pdf
That is excellent, thanks. I agree, track adjustment is a real issue that I over-looked. In response to Komatsu 150 above. On the Cat D3G, you begin by moving the machine forward 2 lengths and stopping w/o use of the brake. The machine is turned off. This is suppose to relax the tracks so they are under normal track tension. You then place a straight edge over the centerline of the track from the idler to the carrier roller (just one on a D3). You measure from the bottom of the straight-edge to the top of the lowest grouser. You repeat this for the distance from the carrier roller back to the sprocket. You add the two numbers together and the sum should be about 80 mm (3.15 inches) for desirable tension. There is a minimum number and a maximum number. Mine was much less than the maximum number. So they were under considerable tension. I can tell you that the machine handles much better and I am not wearing the undercarriage to the extent I could be.
That is the way it always used to be done. We only have track loaders not dozers and the book shows the stroke method at least for our models. We do it the old way but every time the dealer gets it they do it by the book.
I'am new to the forum and appreciate and advise on my question. I have a 1982 Caterpillar D3B Dozer. There is more than three inches of slack in my tracks and need to adjust, but have no idea how to do this. I searched for a service manual, but they cost around $300-$400. Does anyone know the procedure? Thanks! Russ
On a D3B remove this cover on roller frame. There is a grease zert you fill with grease gun. Adjust to the specs above.
JeremiahSr Thanks for your help! I will give it a try tomorrow. Russ