To add to the confusion:
the nicks will affect the seal if the piston ram (the thing with
the nicks) travels past the seal (which is at the top of the
housing) If however, the nicks are, say, at the very top of the
ram and you never let that part travel into the housing and past
the seal, by not collapsing the jack all the way, the damage
will not go any further. I have seen many rams with varying
degrees of damage, most of which are still in service, but
obviously the damage will hasten seal failure, which is a type
of rubber (many different types).
On larger equipment, a damaged ram, unless severe and causing a
leak, is almost always left as is (except for careful
filing/smoothing) because larger rams replacement easily runs
into thousands of dollars. And the seals handle small nicks
quite well, as long as they are not sharp. Larger and smaller
hydraulic rams are similar in construction.
And I suppose I should say that if you want to purchase a jack
with damage because the price is right, the only way to tell if
a 20ton ram is going to leak is to put it under a twenty ton
load. And even then it may not leak this week, but might next.
I’ve seen some leak with slight damage and others not leak with
I was an electric/hydraulic troubleshooter for Food Services of