This method can be used for softer rubber seals. An alternative method for harder rubber seals is posted below.
The ram seals that were supplied by our shop had been manufactured by copying an original seal. They are the exact dimensions of the original but the rubber will feel a little harder than the older seal you are replacing. To fit the seal into the housing, hold the casting firmly in a vice, then heat the casting and the seal at the same time with a hot air gun. This makes the seal more pliable and prevents a cold casting taking the heat out of it as it comes into contact. A very blunt rounded screw driver (mine had been used for raking out brick work for re-pointing) or similar will need to be used with plenty of hydraulic jack fluid for lubrication.
When the seal has been heated right through (to a temperature that can just about be handled with thin working gloves) It will be pliable and should be squeezed into the hot housing with the top lip forced into the housing recess. As above.
The seal now needs to be forced in on its self with your warmed blunt screwdriver and pushed into the housing. It will then pop open to fit into the housing recess.
Fitting the latest version of Jackall Ram Seals December 2020
The jig, plus some of the special tools made to facilitate dismantling and rebuilding jacks including split block for clamping the jack ram to remove/fit the the foot, the bullet tool for easing the ram into the seal and the rear jack clamp for holding the jack body in the vice. Not include were the big vice, the big Stilsons and the 6ft length of gas pipe to slip over the Stinson handle to provide the necessary leverage for loosening the seal housing.
The latest version of Jackall Ram Seals are much stiffer than the original seals and cannot be fitted as some previous (including the original ) seals have been by folding them in half and with plenty of lubricant, heat and brawn forced into the housing. So, a different method has been devised both by Franz Tenbrock in Germany and here in the U.K. The drawings show my version of a jig that has successfully fitted the seals without damage. The drawings are all in Imperial measurement, as most components on a Y type were, I have, however used decimal precision, rather than fractional precision as many of the works drawings were done. I apologise if my layout projection of the drawings (3rd angle etc.) does not conform to convention, I wasn’t trained as a draughtsman!
The materials I used were those that were available to me, and an important dimension, the taper angle was dictated by the travel of the compound slide on my lathe (2.1”) giving an included angle of 16 degrees, a shallower angle nearer to 4 degrees would be better but it works.
Parts Drawings. please click to enlarge
3 dimensions are important on the jig body:
!) The 1 inch bore. The jack ram is 1” dia. The bore of the housing is 1” + 8-12 thousands on a range of jacks I measured. The seal need to go through the 1” hole in the housing so this bore is quite critical.
2) The 1.8 in dia. X 0.25 in deep recess. This is to locate the jig central to the 1” bore on the housing, most of the housings I’ve measured are there or thereabouts and if the recess is made to drawing, a polish of the housing with emery paper should allow the seal housing to fit snugly in the jig.
3) The 1.6 in dia. X 0.9.00 in deep recess. The seal is 1.6in dia. And it should be a snug fit in this recess, a push with the thumb will allow the seal to enter the taper.
When making the rams the tapered ram should be flush, or slightly shy of the end of the jig when pressed into place. Likewise, the solid ram should be flush with the small dia. of the tapered ram when the ¼” bar is in contact with outside of the jig body
Dave Jones
Drawing of tool made by Franz Tenbrock