Home : Technical : Trouble Shooting : Miscellaneous : Warped & Twisted Bullwheels

Construction of a bullwheel:
Bullwheels are welded in a jig, when done they are pretty straight, less than 1/8" run out. After welding the bullwheel is heat treated in an oven. Sort of straight - ¼" run out. Actually this is not too bad for a hunk of metal that is 10 plus feet across and has been flipped over twice for welding. After leaving the oven they are either (depending on model or year built) lowered onto the gearbox drive shaft while hot or shipped separately for field installation. Before shipping the bullwheel liner was ether hydraulically pressed in or pressed and hammered in. Now the flange is just kinda straight 5/16" run out.

Field installation of the bullwheel:
In my time spent in the industry I never saw a bullwheel get unloaded from the truck without the flange touching something, pavement, logs, hay bales, boss's truck etc. - imagine Men In Black, the space ship slamming into the farmers truck. The flange is kinda sorta straight 3/8" run out at this time. After unloading from the semi truck it gets loaded to a boom truck for a ride up the hill to the drive terminal site and yes another source of flange bending probably has occurred on its trip up the hill by improper securing to the boom truck. Then you just plop the gearbox/frame in the bullwheel or turn every thing upside down again and lower the bullwheel down on the shaft. This sounds easy enough but in practice it's raining, late in the afternoon, you have almost run out of either oxygen or acetylene for your rosebud and a host of other small items that make the job even more challenging than it should be. Jump up and down on bull wheel to install. Flange at this time is still at 3/8 but has more humps and dips.

Is your flange a drag - Adjustment checks and tips:

• With brake engaged check for very little play in ram, this makes a difference in how much travel is wasted just extending the ram which reflects on the pad opening. Some rams might have an adjustable piston, this should be screwed all the way in. Remember some play in the ram is needed to insure that the full spring/washer pressure is being applied to flange.
• If you are going to replace worn pad(s) because your flange is bent, check to see if the brake holds at the recommended input shaft torque. If it holds there is no reason to change the pads, there just going to wear again until they clear the flange.
• Be careful of high brake pressures, after a certain point this pressure is only a reflection on how flat you can crush your bellview washer pack, not how much pressure the brake will apply to the flange or any larger clearance you might think your getting!
• If you happen to have the bottom shoe assembly off make sure there is a way for water/ice to drain out of the shoe holder. This is the most common cause for lower shoe wear.If your brake slips try testing it on another portion of the bullwheel and try removing some of the shiny paint that the junior management trainee wanted so that lift looked good rather than ran good.
• The valve that controls the rate of drop or clamping should be tested on a cold day due to the change in oil viscosity. The valve handle should be safety wired in that position, the wire should be obvious to see and you should be able to remove it with gloves on.
• Oil pressure operating range will fluctuate due to temperature extremes and these should be marked on your pressure gage.
• The oil reservoir should be at its lowest when your system has pressure.
• Any water or dirt in the system will migrate to the lowest point; this usually is the last 2' of hose and the ram itself.

Bent flange straitening techniques:
A dial indicator is useless trying to check runout on the flange. A sharp piece of soap stone just touching at 50% speed is your best bet to find the high spots. If the bullwheel itself is bent the old fix was to weld on the top or bottom of the spokes near the hub to shrink that particular side to bring back the wheel into a more familiar round shape. This should be your method of last resort. In fact it is a good idea to check all the weld connections while you're near the flange area.
You can try a jack between the flange and drive frame, little changes are better than a big change in the opposite direction. A bit of caution should be used as you might be pushing the bullwheel off its shaft.
Another method is the heat the flange with a large rosebud (smaller ones take too long and the heat will melt the liner), again your results might not be what you want as some times heat will make the metal shrink as it cools.

Other info:
YAN finally set up his bullwheels on a large lathe for truing flanges in his final production years.

I suspect your doing 95% of this stuff anyway, I hope the rest helps. If you have any more questions feel free to post.