Does more torque make less horsepower acceptable?

[CEwriter]

I recall seeing a post on here somewhere that had photos of the worlds biggest skid steer -- Gehl's 7810 (and Mustang's 2109) -- so I thought y'all might find this interesting.

Gehl just introduced the 7810e, and this new generation of the world's largest skid steer has a Cummins B4.5T-99C rated 99 net hp and 305 lb-ft of torque at 1,500 rpm. The Cummins replaced a Perkins 1104C-E44T rated 115 net hp and 291 lb-ft of torque.

It's a 13% drop in horsepower and a 5% increase in torque. A Cummins for a Perkins. Is that a good trade? What do you think?

Gehl 7810e page

 

[Dozerboy]

I would go for the Cummins TQ is king IMO.

 

[Steve Frazier]

I agree, torque is the driving factor in machinery. I'd take an engine with a higher torque rating over horsepower.

 

[Squizzy246B]

In looking at the power and torque curves for these engines there really is not a big difference. The perky is a 4.4 litre with peak torque at 1400Rpm while the Cummins is a 4.5 litre with peak torque at 1500 Rpm. The Perky produces a peak of 394 Nm while the Cummins produces 414 Nm...just a slight edge to the Cummins. I wonder how they would go on fuel economy.

At the end of the day, with Hydraulic drive it all depends how the pumps are set, and the governor lets the power come on. The factor of gearing comes into it.

I notice Gehl claims "With a 99 hp (73.8 kW) Cummins® diesel engine and a rated operating load of 3,850 lbs. (1747 kg), this is the World's most POWERFUL skid loader."

I thought the RC 100 was around 100 Hp.

 

[Tigerotor77W]

Squizzy, you're correct... the RC100 is 99.5 hp, I think.

However, as power is work per time, perhaps it could be argued that the cycle time of the 7810e with a load is low enough that the work it does as it lifts 3,850 pounds is greater than that of the RC100 to its maximum height?

Who knows. It's all marketing hype...

 

[CEwriter]

A five-percent increase in torque may not be anything to crow about, but I think the point is that the decrease in horsepower doesn't mean a decrease in capability. You and I may read about a drop in horsepower, but the hydraulic pump feels more shaft-twisting power.

Don't forget that it's a 5% increase in torque for a machine that was already firmly at the top of the skid-steer-loader category. The next-largest, non-Gehl-manufactured SSL is John Deere's 332, whose Deere 5030Hw is rated at 85 net horsepower and delivers 251 foot pounds (18% less torque than the 7810E).

Now for a bit of hair splitting . . .

The RC100's Perkins 1104C-44T is rated 99.5 gross horsepower, but Gehl quotes the Cummins net horsepower rating. With peak torque of 304 foot pounds, RC100 is no doubt a formidable machine and virtually equal in power to the Gehl 7810E. But the RC100 isn't a skid steer loader. Compact track loader is a pretty different machine, and I expect buyers pay a very different price than those who opt for the skid steer.

L

 

[CT18fireman]

When you are pushing into a pile of material HP doesn't really matter. The engine is already up to speed and the torque keeps the pumps going. I think HP is overrated in equipment, maybe in mowers it means something where blade and ground speed is important, but in equipment it is usually about capacity and to me that means torque.

 

[Tigerotor77W]

It's good to see this discussion here, as well!

I think torque is generally a clearer measurement of a machine's ability to "push,' but horsepower is the widely-accepted measure of "power," which is why some manufacturers tout engine horsepower instead of listing torques (*cough* Bobcat).

The other thing that affects the torque perception is how it is multiplied through the pumps, motors, and gears. Coupled with a lack of a real industry testing standard (manufacturers publish axle torque, tractive effort, drawbar pull, and push force), it gets confusing to sort out just what means what.

If any of you can clarify, I'd love to hear, as there are some funny numbers published all over the place.

 

[T Red]

I believe HP is the ultimate measure.

(Torque x Engine speed) / 5,252 = Horsepower

if you had 300 ft lbs at a low rpm say 1000rpm you would have about 57 HP.

if you had 300 ft lbs at 1500 rpm you would have about 85 HP.

also the max torque is not at the same rpm as max hp.

as a general rule i prefer low rpm engines. I believe they will last longer. diesels are built for low rpm and good torque. i sure both of these engines would be fine at 1400 to 1500 rpm. some of the early skid steers had high rpm engines, mostly foreign.

i agree most of the differences here would probably be in the machine hydrolics and set up.

just my opinion

tim

 

[Jeff D.]

Another variable that can make two very similiar "rated" engines feel quite differently, power wise, is the % torque rise.

Two engines may have the same peak hp/max torque at the same rpm's, but one could have more torque(lower rise) below peak, and fall off at the same rate above it as the other engine. This wouldn't be shown using only those two rating figures, but would make one engine "feel" stronger at low RPM's, and ultimately give it more useable power below it's peak hp rpm.

That's where graphs would be useful.

 

[Squizzy246B]

I am reminded of an engineering project in the 90's I was involved with. Our Army wanted to refurbish and upgraded their LARC V fleet (amphibious vehicles). The Larc's had the Ubiquitous Cummins 903. So in their wisdom...and against ours...they fitted the Cummins 6BTA5.9...in other words they took out a ...what???..a 10 or 11 litre engine (I can't remember) and fitted a screaming banshee....they could get the power up there but they never had the same slow speed torque the old 903 had. Life expectancy went from 3 or 4 thousand hours down to about a 1000 and overheating was a major problem.