Torque rise numbers- 4520 vs. 4720

[TCowner]

I posted on the New Holland forum that I was trading my TC40DA for a JD 4720 with an add on Curtis cab. Some folks have suggested that I consider the 4520 to drop the cost a bit but then upgrade to the factory ComfortGuard cab. I'm very close to a decision to upgrade to the nicer cab but have a question about the two tractors.

According the University of Nebraska tractor test laboratory the 4720 has just a little over a 5 hp difference over the 4520 but there is a difference in what they call torque rise. The 4720 did not meet the manufacturer's claim of a 30% rise, it had 24.67%, while the 4520 had a 32% torque rise.

What should one make out of this? Are these just numbers that offer little indication of how the tractor should perform or does the 4520 with less hp but the greater torque rise numbers give reason to save some money. The difference in net trade difference amounts to about $1350 the way the tractor is configured. I was all set to give the dealer the go ahead to order the 4720 but I may want to save the money.

Any thoughts?

 

[TCowner]

Just a clarification. I posted about my trade of the TC40DA originally in the JD forum, not the New Holland forum. Sorry,

 

[Gizmo36]

They are at 3700 lbs ,What they will pull will be about the same .So I would get the one I like the best .

 

[orlo]

TCOwner:

I'm no diesel expert but from what I understand "Torque Rise" to be it's the difference between torque at the operating RPM and maximum torque (at a lower RPM). The JD stats only show the torque at the operating RPM and not maximum. Given the 4720 has a higher PSI boost it would make sense it would have more Torque at any given RPM but I'm not sure why the curve would be less steep. I'm sure if you could get the peak figures it would be higher peak on the 4720 over the 4520. Without seeing the actual curves I guess it would be hard to judge.

 

[Cidertom]

I have a 4520, and so far I lose traction prior to loss of power. I have R4 filled and use skidder chains as needed, and have yet to stall it from that aspect. The difference is less than 10% of the total HP between the 4520 and the 4720. When I got mine the only transmission on the 4720 was hydro. I (for purely personal reasons) do not like hydro. So the choice was clear enough for me. I suspect the torque rise is being flatened by the fact that for a certain displacement (the same in all 4x20) there is a limit on how much boost does any good.

 

[JasonL]

TCowner-
I don't have a clue about the torque and/or horsepower of these tractors, but I can speak about the ComfortGuard cab. My dad has a 4720 with cab and it is awesome! If you want a cab, do whatever it takes to get a JD one!

Jason

 

[Turkeyman]

I really do not think 5 hp and 7% torque difference will be that noticable, but a cab vs ROPS will be. My 4720 (no cab) weights about 7500lb with the loader/ bucket on and I alway loose traction ( R4) before it runs out of power, and I rarely run at PTO speed.