It's more 'juddery' than it used to be when rotating and the rear shoes are about 3mm thick. The oil is fine in the circle motor - the shims must have worn out enough to let the circle teeth come back too deeply into the spindle teeth. I think. . I've only been running a grader for eight months...
There is a procedure for setting a circle involving a number or steps that should be done in a specific sequence. PM me with your email address and your machine S/N prefix if you want a copy.
Nige Can I also talk you out of a copy please? I have a 14G, but the DCM is updated to the later model with replaceable wear strips. PM coming with email and serial.
If you’re referring to the wear-strips; 3mm is getting a little too thin for me. When the wear-strips get thin they tend to break easier especially if they’re run too loose. If they break they fall out and now you’ve got steel running against steel or steel running against a casting (in the case of the lower shoe). This will immediately cause scarring to the micro machined smooth surface of the circle. If the circles get scarred then the wear-strips are running against a rough surface and will wear out at an accelerated rate. The circle ring is a single piece forging (in the case of Caterpillar’s) and is an extremely expensive piece to replace. If you keep good wear-strips in there and keep it adjusted properly you can always bring it back to new condition by simply installing new wear-strips and adjusting. The wear-strips are the sacrificial part and it’s designed that way so as to protect the super structure components (circle and drawbar). Wear-strips are cheap; it’s not worth the risk when you consider the cost of the other components. In regards to adjusting the G & H Series Circles: Set the parking brake, ground the ripper if you’ve got one, chock the tires if not. You’re going to be under the machine for a while. I turn the moldboard 90 degrees to the mainframe, tip the moldboard all the way forward and ground the moldboard using float. Then take a hydraulic jack and jack the front ring of the circle up snug against the bottom of the drawbar wear-strips, you can also use C-Clamps to do this if you’ve got big enough C-Clamps. The weight of the drawbar will keep it snug in the back. You want all the clearance on the bottom side since that’s where you’ll be doing the adjusting. Next I drop the center side shoes out of the circle because they cause nothing but problems when you’re setting the pinion depth, removing the center shoes also gives you a little more room to work your feeler gage while setting the vertical clearance on your four corner shoes. Pinion depth is critical and is a unique setting to each size machine, I believe it is 1.97” on your machine (140H?). (look in your OM&M, it will give the setting dimension and the drawing will show exactly where to take the measurement). Pinion depth has to be set so that the shoes/wear-strips are carrying the load and not the pinion shaft. The pinion shaft is designed to take torsional loads not horizontal deflection. If it’s set too shallow, the circle will slide back and put a tremendous load on the pinion shaft which will take out the pinion bearing and seal in a matter of days. Before taking any of the four corner shoes loose; get yourself a good feeler gage with long feelers and 45 degree bends on the ends, check with your feeler gage the vertical clearance (the clearance between the bottom of the circle ring and the top of the lower wear-strip) and right it down for each corner. This will help give you a starting point on how many shims to remove once you start breaking things loose. There are two different size/thickness shims (.010” & .030”) in the stack when the machine is new. Use a dial indicator or micrometer to check the shims thickness. Before removing the bolts from any of the shoes look at the orientation of the shim to the shoe; one end of the shim has a tab the other end has the open ended hole. You can remove just the two bolts closest to the tab end, the other bolt can stay in, but will have to be loosened so that shims can be added or removed as you adjust. This way you don’t have to keep lifting the entire shoe back into place each time you go to re-measure. To re-measure you have to put the end bolts in and tighten the shoe back up with at least a ¾” impact gun, if the shoe isn’t tight the measurement is useless. I turn all the horizontal adjusters in a few turns. Loosen the shoes and push them back slightly from the inner surface of the ring, this is to prevent binding of the wear-strips while you’re setting the vertical clearance. Once I finish adjusting the vertical clearance on the four corners I then adjust the pinion depth. I make a pinion depth adjusting tool from a large flat washer simply by grinding one side of the washer down so that the washer measures the exact dimension that should be between the flanges. I fire up the welder and stick a piece of heavy welding rod to the face of the washer this allows me to keep holding the measuring tool up in the opening between the two flanges as I make adjustments. You only make adjustment an 1/8 to 1/4 turn at a time. You will have to loosen the shoes just enough so that they can slide fore & aft while you’re turning your horizontal adjusters. Once the pinion depth is set the washer/measuring tool should lightly drag between the pinion flange and the inner ring of the circle. Once I have the pinion depth set I then adjust the two back corner shoes to set the horizontal clearance at near 0.0” to 0.010”. With the brass inserts I usually set them at 0.010 and with the graphite impregnated nylon inserts I set to 0.0” . NOTE: in the early H Series OM&M the drawings in the “Circle Clearance – Check Adjust” section are incorrect, the photos are correct. So be careful what you’re looking at. Now with just the four corners shoes in place and set I tighten the shoes up. I fire up the machine lift the moldboard off the ground and rotate the circle to be sure there is no binding effect. If everything moves properly and freely I re-ground the moldboard and fit the center side support shoes in to place and adjust accordingly. First setting the vertical clearance with the shoe pushed back away from the inner ring slightly. Once the vertical clearance is set, loosen the shoe just enough so it will slide when turning the horizontal adjusters. During this entire process I use lots of marine quality anti-seize on all the bolts and adjusters. I also put anti-seize between the top shim and the bottom of the drawbar. The OM&M calls for .020” vertical clearance, I usually shoot for .015” and on some machines equipped with the graphite impregnated nylon wear-strips I’ve even gone as tight as .010” without any problems. It’s a slow tedious process to set it correctly, but it pays great dividends when you’re finishing something like an aircraft parking apron with tight drainage. Have Fun, Randy
Nige, Do you have the procedure for setting a circle on a 130G? Thanks, PWR