The way we used to drive.

The following is an excerpt from an email sent to me during truck school by my Grandpa who drove trucks for many years. I hope that most of you will enjoy his memoir.

Until next time

David

"With the dual transmissions ( a main box and a Brownlipe aux , most brownies were three speed except like the ones we had as we had a couple of hauls that required a deep under drive in the brownie ) which gave us four speeds in the brownie. We only used the top three in normal driving. Fifth gear in the main box was an overdrive. We never pulled in OD ( with your understanding of transmissions you know why) but technically we had fifteen speeds forward. It was most of the time a two handed job. e;i Starting out we used first gear ( to be easy on the clutch ) at 2100 rpm release clutch and pull the main into neutral, pause, then drop the main into second while pulling the brownie into neutral. Engage the clutch and bring the rpm up to match the total power train and clutch the brownie into second and reengage the clutch, Downshifting required pulling whatever box you were changing into neutral reengaging the clutch, bring rpm up to match engine and transmission speeds clutch drop into needed gear and reengage clutch. Continue the same procedure all the way up through all the gears Another thing that is different nowadays is you never exceeded fifteen hundred rpm against compression. The reason was the fuel pump was a double disc pump. It had two highly polished discs with orifices in them that were timed to line up at the correct time to deliver the fuel to the right injector at the right time. The disc surfaces received their lubrication from diesel fuel between them. With a closed throttle there wasn't sufficient lubrication above fifteen hundred rpm and the discs would score thus ruining the pump. Later in my career the PT pump came out ( pressure timing ) The Cummins engines of those days were to be operated between nineteen hundred and twenty one hundred, except against compression. Also there were no Jake Brakes and the Williams exhaust brake was just coming out.,so you went down the hill in about the same gear you came up it,naturally depending on the length of the hill. There was an aux brake that worked well, but it added too much weight. It was a wheel like a water pump on the drive line. There was a valve that was controlled by the driver. It would restrict the flow of water thereby creating resistance to the drive line. It required a large tank of water mounted behind the cab to supply it with cool water. The additional weight cost payload so they were seen on only a few trucks. By the way the first year I drove the speed limit was forty five mph and we also used the clutch brake to make quick upward gear changes on hills. It is a different ball game today with all the traffic plus the new style equipment and big horsepower."