Torque. Is it still around?

challengertn · Apr 19, 2004

I've been sorta' checking out a lot of these new small tractors and comparing them with some of the older models and it has me wondering how these tractors will be a few years down the road. One thing that concerns me is the high rpms these tractors have to operate at to achieve their ratings. I now use a 135 MF and it's pto is rated 540 at 1700 rpms. Some of the new ones are in the 2200rpm range or more to reach 540. Is this high operating rpm going to shorten the life of these tractors? Also, I don't know about tractors but when dealing with cars it usually means that you are short on torque when you have to rely on higher rpms in some of the short stroke engines. Will these tractors pull as well as their older counterparts? Is the front wheel assist used to make up for this in some cases? I still use a tractor for some tillage and I wonder if the fact that small tractors are not used as much for this in this day and time has brought about a change.

Joe1 · Apr 19, 2004

In my case, the MFWD is because I need the traction. I seem to have the power I need so far, I run out of traction first.

TNCHRIS · Apr 19, 2004

i too have a mf135. i have replaced with a L3830HST,slightly smaller then mf135. the next size up is the L4330 it has the same torque as the perkins untill you multiply the engine torque by the pto gearing 3.15 for massey and 4.9 for kubota. the final pto torque is mutch greater with the higher rpm's i have squelled the belts ( 6 foot finnish mower) twice with the kubota in thick grass that would only bogg down my massey. less bogging = less wear. kubota list engine torque in the owners manuals.

normde2001 · Apr 19, 2004

"Some of the new ones are in the 2200rpm range or more to reach 540."

My Yanmar is 25years old and operates at 2200 rpm for 540 pto rpm and still runs like new.

SteveM · Apr 20, 2004

I dont think the high RPM will automatically mean less engine life. I had a 200k mile honda civic that ran perfectly with no oil usage, and that was definately a high rpm motor.

Do they pull as well? If the weight of the tractor is the same, probably. The issue is that most compact tractors are light, and run out of traction before power. I also think the old tractors with big displacement engines had much higher torque numbers than most compact diesels. My ford 2n has 135 ci - that is a big motor, I would guess it might put out more than 100 ft lbs of torque at peak - but I am guessing.

To20Chris · Apr 20, 2004

High RPM does not equate to no torque or to engine damage - it all depends on what the engine was designed for. A low RPM engine with a long stroke, will have oil and coolant pumps designed for proper pressure and circulation at low speed. If you rev it too high, you'll wear it out quick, because the reciprocating parts are not meant for the increased forces. Also the high piston speeds and lateral force on the cylinder walls will wear the cylinders & rings.

A high RPM engine will usually have a shorter stroke to keep the piston speeds and reciprocating forces down, and the pumps will be set up appropriately. If you bog it at low speeds, you'll pound the rod bearings because the oil film may not be sufficient, and the short stroke means there is less leverage on the crankshaft. Once you push through the oil film, the bearings won't last long.

If you gear the high RPM engine down, you'll get the torque back. In general, the high RPM engine is physically smaller and lighter, and I imagine that is why they're used CUTs. Either approach can work, it's really just a matter of using it as it was designed to be used. I think the Perkins diesel in the MK135 has a 5” stroke – now that’s a serious long stroke!

fire72 · Apr 20, 2004

I just traded in my '74 MF 135 on a '99 New Holland 1920. I actually lost PTO HP in the deal, from 37 with the Massey to 29 with the NH. Overall tractor weight stayed roughly the same; the NH is a lighter base tractor, but has an FEL making up the weight difference.

The Massey ran like a top, but I always had trouble with traction, particularly doing tillage. My 2-14 plow was just more than it could easily handle without spinning the tires constantly. If I raised the plow enough to keep the tractor moving, I didn't have enough depth to roll the sod under. The NH, even with less HP, pulls my plow and 6' disk far more easily because of the FWD.

It just comes down to the type of work you're doing and whether traction is more important than HP. Although I loved the Massey, the NH is light years ahead for my tillage work. Haven't done any PTO work with the new tractor yet, but I don't anticipate any trouble swinging a 5' bush hog.

JerryG · Apr 20, 2004

If I had a choice, I would much rather have that long stroke Perkins in a compact, than any of the engines that are available.

KiotiJohn · Apr 21, 2004

( If I had a choice, I would much rather have that long stroke Perkins in a compact, than any of the engines that are available. ) I find it interesting that Kioti uses the Perkins in their DK65. I drove one recently at my dealer's and it's really sweet. Great, strong, TORQUE. Wish I had a need for that size tractor. John

RalphVa · Apr 21, 2004

Our 1983 Benz is revved to its red line in 1st gear (about 4,300 rpm) almost every time we pull out and up near red line in 2nd gear. It still starts and runs like new.

I'd be more concerned about its effect on you with the louder engine at a little higher rpm. Most diesel tractors I've heard, though, are quieter than the 12 hp Kohler engine on my Gravely. Think they wanted it to sound like a 1960s Fiat, which were usually loud. ALWAYS use ear plugs when using engines. Otherwise, you may be like me with a bionic ear that had its guts replaced with metal/plastic parts. NOW, those parts are really sensitive to loud noises.

Civics, Honda, Volvos & Benzes with 4 cylinder engine regularly go up around 300,000 miles between overhauls. In Europe, they run them at 100 mph, too. We're stupid here in the US. We buy engines and don't use their full power, paying a lot of money for the initial purchase and loss of efficiency to a loafing engine.

Ralph