MAHLE RTI ATX-2PS - Manual (Page 14)

Page 13
ATX-2 Calibration
The ATX-2 is a sophisticated electronically controlled machine for exchanging transmission fluid. The
ATX-2 is connected in series with the transmission fluid flow at the cooler hose. The vehicle
transmission pump now pumps used fluid into the ATX-2 used fluid tank and the ATX-2 pumps new fluid
to the transmission from the tank of new fluid in the ATX-2. Transmission pumps vary in their flow rate
from vehicle manufacturer to manufacturer. This requires that the ATX-2 monitor the old fluid coming
from the transmission and in turn pump new fluid back to the transmission at the same rate.
The used and new fluid tanks in the ATX-2 each sit on a weight scale (load cell). The increasing weight
of used fluid is monitored by the electronic controller which in turn controls the speed of the ATX-2
pump which is pumping new fluid back to the transmission. The accuracy of new fluid pumped in
compared to old fluid coming out of the transmission is within 1/4 quart during the exchange process.
So, the function of the ATX-2 is to pump new fluid into the transmission as the transmission pumps out
used fluid at a rate that will keep the transmission happy. Not too much and not too little. This occurs
with the design of the ATX-2 in a near-perfect world. So, what is the real world?
The real world must consider the following:
1) Not all new transmission fluids weigh the same. They are very close.
2) Old transmission fluids can have different weights. Really old fluid can have a lot of solids
suspended in the fluid and be very heavy.
3) Not all transmissions pump or control the flow of fluid in the same way. Some are very slow
(Dodge Durango). Others cycle the flow of fluid off and on to the cooling lines dependent on
the temperature of the fluid (Ford Explorer). Both of these examples might make the
technician think the ATX-2 is not operating correctly because it takes so long to do the
exchange. The procedure can be speeded up by accelerating the engine to 2000 RPM
during the exchange.
Real world factors may cause the technician to believe the ATX-2 is defective. He does an exchange
and the transmission is under-filled or overfilled. Therefore the ATX-2 must need service or calibration
of the load cells. NOT SO. It may simply be the fact that the old transmission fluid was very heavy per
quart (due to the contaminates suspended in it) compared to new fluid. Remember, the ATX is pumping
new fluid based on weight, so in this case it would pump in more new (lighter) fluid and the transmission
would be overfilled.
These real world inconsistencies are known and therefore the reason for the add or remove ½ quart
feature which is built into the ATX-2.
Then there is the issue of the level viewing slots on the sides of the ATX-2. These slots are
provided so that the technician can see the fluid levels in the tanks. The scales next to the slots
approximately indicate the number of quarts in the tank. The only purpose of these slots is to
give the technician an idea of when the used fluid tank might need to be emptied or how many
bottles of new fluid to bring from the supply room to fill the new fluid tank.
It is a gross error to pour new fluid into the new fluid tank to the 12 quart level and expect the
ATX-2 to do a 12 quart exchange. Some of the reasons why the levels seen in the tanks may
not coincide with the results of the electronic control indications are:
1) New tanks vary slightly when molded. Some bulge out at the sides more than others.
2) Mounting height of tanks can vary slightly.
3) Machine may not be level because of floor or under-inflated tires.
4) Hot transmission fluid may cause the sides to bulge slightly.