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. YOUR SHOP
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Mark before you split
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Punch-marking the |
Save time and future trouble by marking every drive shaft on your equipment to make sure it stays “in phase” if you ever have to split it apart to replace the universal joints.
This preventive marking is simple. Get a sharp point-punch and a stout hammer, and make an equal number of punch marks on both sides of the “yoke” as shown in the photo. Make a different even number of marks at each of the yoke-pairs in the drive shaft assembly, and make sure you mark only one mating set on each side of the joint.
The yokes are a relatively soft steel, and the marks won’t hurt a thing. A dab of paint helps identify the matched sets.
Before a drive shaft leaves the factory, it is “trued” and balanced. Specialized machines and highly skilled technicians compensate for minor variations in the drive shaft tube and the yokes welded to each end, so the assembly rotates at high speed without wobbling or vibrating.
Without punch marks to guide you, it’s easy to flip one of the yokes upside down when you replace the U-joints. An out-of-phase rebuilt drive shaft will wobble and thrash, and you’ll have a nightmare trying to figure which of the four yokes is flipped. If you’re working with a two-piece drive shaft, a headache becomes a nightmare.
The Internet site http://en.wikipedia.org/wiki/Universal_joint does a nice job exploring the physics and math involved.
I prefer to use even numbers of punch marks and a different number at each end of the tube. If one mark gets rubbed off during use, it’s obvious that a face with three dots mates up with a face with four marks, and not one with two marks. This will avoid flipping the drive shaft tube end-for-end and making a total mess of the deceptively simple-looking system we use every day to transfer engine power to wheels and turf-care implements.
When the drive shaft runs between a tractor’s power take-off (PTO) and an implement like a brushcutter, the implement will move up and down while you drive over rolling terrain. These drive shafts will include a “telescoping” section that allows the shaft’s length to grow and shrink.
When rebuilding one of these drive shafts, be very careful to keep the telescoping section lined up correctly.
Do not use a punch to mark the splines in the telescoping section. Those splines are made of hard and rather brittle steel. Even if a punch will put a mark on the steel, the displaced edge of the punch mark might prevent smooth sliding of the splines.
Instead, use a small rotary grinder to make a tiny divot in one of the splines and a matching divot on the outside tube that mates with the splines. If no grinder is handy, use a sharp file to make your mark and keep things lined up.
Areas used to wash mowing equipment after each use to remove grass clippings, a common exercise at golf facilities, are closely scrutinized for potential environmental impact such as ground or surface water contamination. Equipment washing often dislodges petroleum products from grease fittings, engines or hydraulics systems, and equipment-washing stations are often located near surface bodies of water, increasing the chances of contamination from grass clippings that contain nitrogen and phosphorus. Owners and operators are liable; they can face large penalties and end up responsible for damages and clean-up costs. A well-designed equipment washing area will minimize environmental impacts and limit facility liabilities. Owners also can choose from a variety of options to handle wastewater, from equipment that cleans and reuses the wash water or removes it from the site, to systems that discharge the water to a turf area for percolation into the soil. For more information about compliant equipment-washing practices, visit www.gcsaa.org, click on “Solutions/Tools” on the left-hand side of the page, and then click on “Compliance.” |
