Participants
–
Zack Bishop; Ron Brock; Bob
Campbell; Kevin Carabell; Brad Carter; Mark Cooper; Chris Castanien; Jeff Clark;
Riccardo Conti; Pat Fetterman; Eric Garzelloni; Ken Goshorn; Jim Gutzwiller; Jim
Matasic;
Discussion
–
Mark Cooper started by asking Volvo
Powertrain for an update on the design criteria of the E7 connecting rods. Greg
Shank replied that the data does not exist, but Ken Goshorn observed that for
years these rods had been run in internal tests at 3200 psi firing pressure with
no bearing cracking. He also noted that in field service they have never run
beyond 2700 psi. Ken also clarified that a two dimple rod has not necessarily
been re-maned twice. It simply means that it fits in group II which is up to
0.010 inches shorter than print.
A discussion regarding rod bolts
suggests that there may have been a change in supplier, and Ken agreed to check
that out. However, he also noted that there has been no indication that the
bearings are moving in the bore, and he doesn’t think there is a bolt
problem.
Jim Mortiz reviewed data showing
that at least one bearing from batch V seems to have a significant scratch on
the outside, and he reviewed Ra and PDI data showing an Ra of 137 with the
groove and 80-90 without the groove. These measurements are well beyond the
Mahle spec of 63 max on the flat stock.
This led to a lengthy discussion
regarding Mahle’s ability to control backside roughness to a lower level. It was
concluded that their manufacturing cannot control to a lower limit, but it may
be possible to inspect for “smoother” bearing
backs.
During another lengthy discussion
regarding how to get “smoother” backed bearings, Mahle indicated that these
bearings are routinely run in monthly batches of 4 to 5K units for Mack Service,
and we discussed whether it might be possible to “intercept” some of these
bearings and screen them for possible T-12 test usage. Bob Campbell noted that
he thinks the batch V bearings may well be the exception to standard “smooth”
back bearings, and it may well be possible to use service parts as long as they
are picked from a single batch.
Throughout the call, the Mahle
representatives were in contact with their plant; and they reported that, in
fact, the plant is currently running a batch of bearings for Mack Service. Eric
Garzelloni indicated that they should know later today how many bearings are
being produced and at what stage of production the order is
in.
Tentative plans to “look” at these
bearings and see how they compare to our desired “smooth” back were discussed,
and we agreed to hold another conference call next week to review whatever
additional data is available by then.
That call is planned for 2:30 pm EST
on Wednesday, January 19th, and Greg Shank suggested that we postpone
our planned face to face meeting which had been planned for the
25th.
Tom Wingfield suggested that Mahle
could look at the measured backside roughness on the 1/10 dated bearings to see
if, perhaps, they may have run at the high end of allowable roughness. Eric
Garzelloni agreed to look, but he doesn’t know how much data is
available.
Again, next teleconference is
planned for 2:30 pm on January 19th, and joint meetings of the Mack
and Cummins Panels will be held at the call of their
Chairs.
Respectfully
submitted,
Pat