Thread: Interesting, Odd or Funny Pics II.

Originally Posted by p38arover

Ian, re the Peterbilt:

Is 60mph at 1500 rpm good or bad?

Why would they make a prime mover with such a long wheelbase?

both.

good on long flat runs it would be right about on the peak torque/peak effeciency revs for the engine.
bad on hills it'd drop out of the top cogs far to quickly

Originally Posted by p38arover

Ian, re the Peterbilt:

Is 60mph at 1500 rpm good or bad?

Why would they make a prime mover with such a long wheelbase?

Originally Posted by donh54

Many US states are only concerned with the length of the trailer, not the prime mover. Longer wheelbase means a more comfortable ride, and room for a bigger sleeper cab, with the expense of manoeuvrability in tight spaces!
The old Cummins donks used to rev to 2100 before they hit the governor. 1500rpm at 60 mph would mean it would probably be geared for about 70 - 75 mph flat to the floor. Interesting on rag tyres and broken bitumen!

Originally Posted by Blknight.aus

both.

good on long flat runs it would be right about on the peak torque/peak effeciency revs for the engine.
bad on hills it'd drop out of the top cogs far to quickly

Excellent specs, the diffs only appear to be 40,000 lb though, shame about the crappy Paccar cab.
Ron, 1500 rpm/60 mph is as good as it gets, 1500-1550 is the sweet spot, particularly for those older 14 L/855 cu in Cummins.
Dave, I'm not sure if that 13 is an overdrive, the knob indicated a direct, but it's an easy mod to overdrive or even double overdrve a 13 or 18 speed. It's a quick and easy clutchless change from O/D to direct, to keep it on song.
I had a similar specced White running 5.28 44,000 lb Rockwells and RTO 12513. I changed the diffs to 3.7s, which took it from an unstoppable 98kph slug to a 158kph rocketship.

Originally Posted by V8Ian

Excellent specs, the diffs only appear to be 40,000 lb though, shame about the crappy Paccar cab.
Ron, 1500 rpm/60 mph is as good as it gets, 1500-1550 is the sweet spot, particularly for those older 14 L/855 cu in Cummins.
Dave, I'm not sure if that 13 is an overdrive, the knob indicated a direct, but it's an easy mod to overdrive or even double overdrve a 13 or 18 speed. It's a quick and easy clutchless change from O/D to direct, to keep it on song.
I had a similar specced White running 5.28 44,000 lb Rockwells and RTO 12513. I changed the diffs to 3.7s, which took it from an unstoppable 98kph slug to a 158kph rocketship.

stock they were direct only but there was a bolt on/in splitter that could give you underdrive-direct or direct-overdrive That'd've been magic.

I always liked the look of the peterbuilts but prefered the Mack drivelines

Originally Posted by Blknight.aus

I always liked the look of the peterbuilts but prefered the Mack drivelines

I stopped liking them after watching Duel!

Originally Posted by p38arover

I stopped liking them after watching Duel!

you know they found it right?
YouTube

Originally Posted by Blknight.aus

stock they were direct only but there was a bolt on/in splitter that could give you underdrive-direct or direct-overdrive That'd've been magic.

I always liked the look of the peterbuilts but prefered the Mack drivelines

Correct Dave , a 13 is a nine speed with an extra bit bolted to the back, enabling splitting the top four, in the overdrive. It's been over thirty years since I've driven, or even seen a 13 direct, I can't remember the shift pattern, but I assume on the direct, the exta bit is an underdrive, enabling splitting the top four.