Case 644 loader repairs

[FUTZ]

You found the o-ring sizes, how go to this web-site https://herculesca.ca/product.php?name= ... &cat=15606 and determine your wiper size.

I can get all seals for both cylinders for <$50.00. What size o-rings need backups?

[Eugen]

Thank you @FUTZ! The -326 needs backing on both sides. It's 1-5/8 ID, 2 OD and 3/16 CS. I can use wiper seals there too or the backing rings are special?

[FUTZ]

The job of the back-up ring is to stop the O-ring from extruding. O-ring extrusion is when the pressure pushes the o-ring into the small gap between the piston and the cylinder wall. The purpose of the wiper is to stop foreign material entering the cylinder when the rod retracts. It is not a seal, but instead "wipes" the rod. There are other devises, such as Polypaks that look a little like a wiper, but are seals. Polypaks have a blade that wipes the cylinder wall clean, are considered zero leakage, and don't require a backup, but the size of the piston groove must be appropriate for the seal used.

I need to know the dimensions of the wiper groove. Your wiper is cracked/broken.
download/file.php?id=6974&mode=view

[Eugen]

The job of the back-up ring is to stop the O-ring from extruding. O-ring extrusion is when the pressure pushes the o-ring into the small gap between the piston and the cylinder wall. The purpose of the wiper is to stop foreign material entering the cylinder when the rod retracts. It is not a seal, but instead "wipes" the rod. There are other devises, such as Polypaks that look a little like a wiper, but are seals. Polypaks have a blade that wipes the cylinder wall clean, are considered zero leakage, and don't require a backup, but the size of the piston groove must be appropriate for the seal used.

I need to know the dimensions of the wiper groove. Your wiper is cracked/broken.
download/file.php?id=6974&mode=view

Best I could measure the groove by making a playdoh mold is 0.1 width and 0.115 height.

I'll try to measure the broken wiper seal. Here it is, best I could measure it. Probably somewhat worn out though.

The width of the groove on the piston, where the backing rings should be is 0.41

I'll browse the Hercules site see if I could make sense of what they have.

[Eugen]

I'm slowly finding parts on the hercules site. @FUTZ quick question: 70 durometer o-rings ok for this cylinder? I've searched on google and I found mentions that 70D is most likely fine, but could not find a clear confirmation it would be the best choice for the piston, for instance. Not sure if I should choose the 90D o-ring.

There are two things that slightly confuse me about the piston o-ring. The piston groove width is about 0.41 inches, and 1.625 diameter. As far as I can measure, the only standard size o-ring that would fit there the dash 326 which has nominal ID 1-5/8, and nominal cross section 3/16. The actual cross section is listed as 0.210 +/- 0.005. So, if the groove is 1.625, plus twice the actual cross section would give 1.625 + 2 x 0.210 = 2.045. If the cylinder tube inner diameter is 2 inches, is 0.045 enough squeeze to provide the necessary seal at such pressures? I could not find a standard o-ring size that is a tiny bit bigger.

Also, the backup rings are a little confusing re dimensions. If the groove width is, as far as I can measure, 0.41", and the o-ring actual cross section 0.21", then we're left with 0.2" space. I'm assuming one backup ring on each side of the o-ring, each in a space of approximately 0.1". Does it make sense to look for a backup ring that is slightly larger than 0.1" so that the o-ring is a little squeezed from the sides?

[Eugen]

Well, I guess I might have just answered my own question, regarding the backup rings. Duh, I see the part number of backup rings near the size I thought would make sense are like "575-326" so, I'm thinking it's not a coincidence that the o-ring size that should fit there is dash 326.

But, there are several types of backup rings:
576-326 split nylon
573-326 55D HYTREL
574-326 90A BUNA-N RUBBER
575-326 95A DUROMETER URETHANE
575-326ST PTFE split
575-326T PTFE solid

If I knew nothing about this I guess I'd choose the 95A durometer urethane or the 90A buna-n rubber. Any opinions?

[Eugen]

So I got really excited having found all the parts to overhaul the cylinders on the herculesca.ca site.

was ready to place an order, and then... they seem to only sell to businesses, they ask for a purchase order.

[DavidBarkey]

So I got really excited having found all the parts to overhaul the cylinders on the herculesca.ca site.

Screenshot 2022-12-28 at 18.08.21.png


was ready to place an order, and then... they seem to only sell to businesses, they ask for a purchase order.

You can order through Rush Hydralics in Midhurst and pick them up your self in Barrie . I have done that in the past .
It is a pain .

[Eugen]

You can order through Rush Hydralics in Midhurst and pick them up your self in Barrie . I have done that in the past .
It is a pain .

Thanks Dave! Pretty frustrating to find all the parts I need at a great price, just can't buy them directly. I'll figure something out. I wonder about the people that bought Grizzly, as they also seem to sell only to businesses. Probably through a local shop as well. I'll figure something out. In the end, the little guy may just swallow the bitter pill and pay more and get it through someone else. It is what it is.

[DavidBarkey]

You can order through Rush Hydralics in Midhurst and pick them up your self in Barrie . I have done that in the past .
It is a pain .

Thanks Dave! Pretty frustrating to find all the parts I need at a great price, just can't buy them directly. I'll figure something out. I wonder about the people that bought Grizzly, as they also seem to sell only to businesses. Probably through a local shop as well. I'll figure something out. In the end, the little guy may just swallow the bitter pill and pay more and get it through someone else. It is what it is.

Is there a farm / equipment repair service up there you can buy through ? Maybe a mobile guy .