What is redline for a typical compact?

[tuolumne]

My JD 3520 is designed to run at 2600 rpms all day long...that's the pto setting. I've never gone much above this for any reason, but is it OK? There certainly seems to be movement left on the throttle (foot throttle maxes out at 2600) and the tach goes up to 3000.

The question arose when I was taking the machine a couple miles over hilly roads with the backhoe on and a 450 lb rear blade strapped in the loader bucket. I would guess the total machine weight at that point was over 8000 lbs. At that weight, it will not pull all the hills in fourth gear. However, I found that if I bumped the throttle past the 2600 just before the hill, and then gave it a bit more as it began to slow down, I could stay in 4th without lugging down. Is this a safe practice for the machine? Could I take the throttle even higher to prevent any lugdown in this situation?

Thanks.

 

[Bird]

In my opinion . . . you won't hurt a tractor by going full throttle. Every one I've ever used had a governor that wouldn't let it overrev. You usually have a couple of hundred rpm available above the rated PTO speed.

 

[tjkadar]

During transport, I'll use full throttle on my machine. If you're going down a big or steep hill, watch the rpm so you don't pick up enough speed to over rev the engine. Never had a problem...

 

[art]

Engines redline depend on the design and the metals used and the end part is the fuel injection system.

There are engines that are only designed to turn at 2000 and yet I've worked with diesels that were put together well enough to spin to 4,500 with ease and were balanced so well from the factory they were good to 5,000!!!

 

[pat32rf]

Most of the time my JD4300HST runs at 1500-2000rpm in mid range for puttin around the yard and bush (no real load). If I'm road running in high range though its 2600rpm minimum. If I come to a hill it won't pull without lugging down I lift my foot until the rpm stays up. Got 3300hrs on it so far, no problems with the drive-train. That difference between 2000 and 2700 seems to make a real difference in torque in high range.....

 

[Wombat125]

The early 400 series and SBU Unimogs came with a N/A 5.7L OM352 motor set for 2800 rpm full throttle. Ag guys routinely turn them up to 3000-3200 rpm. The exact same motor runs 3500 rpm in industrial applications.

If there is any consistency among design engineers, I'm guessing that there is no way you could possibly hurt your tractor with high revs as it comes from the factory.

Ok, *maybe* if you started a gear tractor in road gear at the top of a really steep hill and over-reved the poop out of it.

 

[tuolumne]

Thanks for the replies...I do see that the torque curve is still giving me a decent increase in power past pto rpms when in top gear.