Today we’re focusing on a simple, yet commonly misunderstood component: the Gartech roller bearing yoke.
One of the features of Gartech Heads & Yokes includes the ability to replace the roller bearings located inside the pockets of the yoke. While we offer bearing gages for every yoke we design and encourage our customers to maintain and rely on these gages, you can also set a bearing using a precision surface and a dial indicator that measures in thousandths increments. But first…
When should you replace a bearing?
If the roller bearing has a shine across its face with noticeable ledges or steps, it’s time to replace. If your yoke shows signs of heat damage, it’s time to replace the entire yoke. If your bearings are held together by high hopes and paper dust? It’s definitely time to replace the bearings! The yokes are designed to last and the replacement components are marketed at an affordable cost. Maintain the parts, replace as needed, and you’ll get years of service from the yokes.
Now, we’ll be working under the assumption that the yoke is removed from the head and taken to a workshop or maintenance bench. This is the safest option, and the most accurate. Because our yokes aren’t “handed” and fit either side of the carrier or mounting plate, it’s useful for you to know which panel you’ll be installing this yoke on ahead of time. We’ll explain why further on in this article.
Preparing for the job
The patented-design of a Gartech yoke incorporates (2) stationary or fixed roller bearings on modified straight pins. These are the innermost bearings on every Gartech yoke.
Random fact: Early designs sometimes featured only a single fixed roller bearing, common amongst our retrofits on Koppers.
The two outermost roller bearings are fitted onto cam pins. If your yoke has 1″ or 1-1/8″ diameter roller bearings, all (4) (or 3, as we covered) require a 3/32″ Allen wrench (non-radiused if possible) for the setscrews and a 5/32″ Allen wrench to adjust the cam pin. If your yoke has 1-1/2″ diameter roller bearings, they require a 1/8″ Allen wrench (non-radiused if possible) and a 3/16″ Allen wrench to adjust the cam pin.
The reorder numbers are:
GAR-009K1 1″ Yoke Components kit
Includes: CYR 1 S 1″ diameter Roller Bearing (4x), GAR-008 5/16″ Cam Pin (2x), GAR-009 5/16″ Straight Pin (2x), #10-32 Brass-tipped Setscrew for Cam Pin (2x), #10-32 Setscrew for Straight Pin (2x)
GAR-009K2 1-1/8″ Yoke Components kit
Not for use on worn 1″ grooves!
Includes: CYR 1 1/8 S 1-1/8″ diameter Roller Bearing (4x), GAR-008 5/16″ Cam Pin (2x), GAR-009 5/16″ Straight Pin (2x), #10-32 Brass-tipped Setscrew for Cam Pin (2x), #10-32 Setscrew for Straight Pin (2x)
GAR-009K 1-1/2″ Yoke Components kit
Includes: CYR 1 1/2 S 1-1/2″ diameter Roller Bearing (4x), GAR-003 7/16″ Cam Pin (2x), GAR-010 7/16″ Straight Pin (2x), 1/4-20 Brass-tipped Setscrew for Cam Pin (2x), 1/4-20 Setscrew for Straight Pin (2x)
Please note: The cam pins use a setscrew fitted with a brass-tip to keep from damaging the surface. Once the surface becomes gouged or burred, it causes damage to the yoke’s pinhole. We mention this so you’ll use the appropriate setscrew and watch for markings in the yoke when replacing pins.
In a perfect world, our customers buy their replacement parts for our products from us. In reality, we locked the delusional new kid outside while we pieced together this topic. If you want to purchase your own bearings, we do recommend using McGill brand for their quality, tolerances, and lifespan.
On a serious note, however: Please respect that our yoke technology is protected under patent. Having another shop or vendor copy or reproduce the yokes is an unlawful, punishable choice.
Now that that’s out of the way…
Using the Bearing Gage
Near the outermost bearing pockets, on the face of the yoke, you’ll find tapped holes that don’t appear to serve a purpose. These are added for mounting our Bearing Gage to the yoke. In most cases, they’ll be the same size as the setscrew that secures the pins. So, either a #10-32 or a 1/4-20 bolt. Since these are bolts and not setscrews, you’ll want a larger Allen wrench. The #10-32 bolt uses a 5/32″ Allen and the 1/4-20 uses a 3/16″ Allen. In 99% of the bearing gages, you’ll be able to use a bolt that’s 1″ in length (not including the head).
Secure the bearing gage in a position where the outermost bearings correspond with the recessed pads on the bearing gage. Don’t have a bearing gage? You can always request a quote by contacting us through the site.
Trick: If you find that your bearing gage only bolts from one side of the yoke, and that side isn’t the one you need, add .004″ shim stock between the bearing surface and the pocket. With worn heads, you might need to add more. We don’t recommend more than .015″ of wear, by the way.
Using an indicator
We’re going to post another entry on this because it’s more involved than using a bearing gage. We’ll also try to post a video on our YouTube channel covering these options.
What direction should you turn the bearing?
The cam pins revolve in a 360-degree fashion, raising and lowering the bearing out of the yoke pocket to contact one side of the yoke groove. This should be the side opposite of the stationary bearings. You’ll create a staggered or offset appearance that helps stabilize the head and allow for smoother rolling.
Gartech recommends adjusting the cam pins in a direction that opens up the gap between the yoke and the head’s working hardware. While the gap isn’t profound, it does let you provide as much space as possible for clearance issues, hardware conflict, and trapped scrap. Once you’ve set a new yoke, it never hurts to inspect the other yokes on that panel to be sure they’re set in the same direction. Doing this keeps slots and scores on-center as designed (unless you’re running offset scores, of course).
Can the yoke be adjusted too much?
You won’t wear out the yoke or the cam pin by hand. However, we strongly discourage the use of power- or air-ratchets. Also, if you over-adjust the bearings, you can reshape the U-style yoke groove into a V-style. This shortens the life of the parts. Read the rest of this article, and we’ll cover the best ways to avoid over-adjusting.
Working at the machine?
When you’re inspecting a yoke while it’s mounted inside the head, we offer these recommendations:
First, use caution. Be sure your plant allows this procedure. There are many unseen points and surfaces inside the compact design of a slotting section. Be aware of sharp edges, knives, bolts, stand-offs, pinch-points, and any surface that might injure your hands. It’s for this reason that we’ll always recommend you use the previous methods we’ve discussed.
Second, make the job easier by using a piece of shim stock or a feeler gauge made from .002″ thick material and free of burrs or jagged edges. If you aren’t using a pre-fabbed set of gauges, something wider and longer than the working surface of the bearing will suffice. On a proper set, you should be able to set the gauge between the bearing and yoke groove, and still turn the bearing by hand.
Keep in mind that the area of the bearing that makes contact is minimal, so you won’t have to waste your supply of shim stock. You’ll also want to be sure the mating surfaces of the head’s yoke groove, yoke ring, or wear plate are not worn in a manner that prevents you from testing with a flat surface.
Remember, shafts move up and down too
On eccentric or adjustable shafts–often lower creasing and lower slotting shafts–make sure that the shaft achieves the height and depth you need. If it rests against the inner radius of the yoke, this is going to damage parts and tear-up more than a yoke.
We recommend that at least 1/2 of the bearing width engages inside the yoke groove of the head. They don’t have to be “buried” to be effective, but too little can cause “slipping” and misalignment of panels. Also, we’ve found it’s best to have 75% of the bearings engaged with the head. Some eccentrics don’t allow for this, so you’ll want to inspect the yokes on those shafts with more frequency.
When brand-new bearings won’t matter?
A groove in either side of the head’s yoke groove, yoke ring, or wear plate exceeding .015″ in depth will not allow for proper setting. This tends to happen from “forcing” parts together during production or when moving panels. Try not to use the yoke as a “driver” or “doorstop” to overcome bad knives, worn shafts, and nuts, or other faults. This results in damaging more components than necessary and makes more work for the operators and maintenance staff.
A perfect fit?
Remember we mentioned over-adjusting? When you’ve set all the bearings and the yoke is fitted, each bearing should turn freely by hand. If not, adjustments should be made. Always be sure there aren’t gouges or build-up of ink and dust between the yoke and the mounting surface. This “twists” the yoke out of alignment, and undoes your hard work. Also, it never hurts to make sure the yoke is flat. While we inspect every part we ship, we cannot control the drops, tosses, crushes, and punts that occur once the courier takes over.
If you can’t turn a bearing by hand, it’s going to introduce heat into the other components once you start running boxes. In some cases, we’ve seen yokes “glow” from the level of heat. This is never safe! If you see this, it needs to be corrected. Please, though, wait for the yoke to cool off before handling or adjusting.
There’s a lot of information to consider here, and every few years we see something we’ve never encountered before. Check back with this article, or other useful topics, and we’ll add or link to additional discoveries and tips as we find them.
And, if you’re still confused, more confused, or just don’t want to hassle with it on top of everything else that needs attention, send us an email. We offer service calls on all Gartech components.
Thank you for your time today. And, maybe remind us to let the new kid back in. Or not.
Need a printable layout? Click here for general setting instructions.