engine brake while towing?

wilber1 wrote:



I thought you knew how pumps work. The flow a pump can produce at a given pressure is directly related to how fast it is turning. The exceptions are variable displacement pumps which can maintain a constant pressure as RPM and demand varies over a fairly wide range. The 68RFE doesn't use variable displacement pumps and neither do any other automatic transmissions I know of.

I do know how pumps work, but what you are talking about here has nothing to do with the fact that it is the transmissions pressure control solenoid/valve that controls the line pressure used to shift the transmission, and not the pump pressure from its higher RPM controlling shifting like you are claiming. I know you want to go off topic so you don't have to admit you were incorrect on this, but no matter how off the loop you go the facts still remain the same that a transmission pump does not control the line pressure that makes the truck shift or delay a shift. In fact, the pump provides too much pressure in many cases for safe shifting and the pressure control solenoid has to decrease it in order to shift correctly and at a certain time.

"The 68RFE is somewhat unusual
in its components: To help reduce pressure
losses, the transmission includes
a dual-stage transmission fluid pump
with electronic output pressure control.
Under most driving conditions, pump
output greatly exceeds what’s needed
to keep the clutches applied.

The 68RFE pressure control system
monitors input torque and adjusts
the pressure accordingly. The primary
stage of the pump works continuously;
the second stage is bypassed when
demand is low. The control system also
monitors input and output speeds: If the
computer sees the clutches slipping, it
adjusts the duty cycle to the pressure
control solenoid, increasing pressure in
proportion to demand."

Meet the 68RFE

So, you going to provide that evidence that states that the pump controls the line pressure used to shift? I am still waiting.....