Ram4x4
Silver Member
Since HP is a calculated figure derived from the torque and RPM relationship you can calculate it out for any given HP rating, or figure any of the values as long as you have the other two.
HP=torque x RPM divided by 5252.
Torque output at a drive point (wheels or PTO) is going to be a function of the gearing ratio since gearing is just round levers and we can trade RPM for more torque or vice versa using different gear ratios. Since the PTO should be running at 540 RPM, and we have the rated PTO HP, we can calculate the output torque at the PTO.
Mahindra rates the PTO HP on the 5035 gear models at 43HP, so our equation would be:
43HP=540 RPM X ??? lb-ft / 5252
5253 X 43 / 540
225836 / 540
418.12 lb-ft of torque at the PTO on those Mahindra 5035's.
Engine torque is really irrelevant since it's all going to run through various gearing which will make the trade offs in RPM and torque to get the desired speed at the drive point. That's why we rate engines in HP. It is a rating that indicates an engines ability to do work.
Diesels are high torque engines and they have to be in order to make equivalent HP to gas engines because they are RPM limited. Diesels just don't turn the higher RPM a gas engine does, but HP is still HP. So, you make a lot more torque, but you have to trade it off for RPM at the drive wheels (or PTO).
The 5.9L Cummins in my Dodge Ram makes 600 lb-ft of torque, way more than a 360cu-in gas engine, but it makes that torque at only 1600 RPM, so the transmission has be geared to trade off a lot of that torque for RPM at the rear wheels to reach highway speeds. It's a torque beast, but it's still only rated at 325 HP because of the low RPMs. In other words, due to the gearing, at normal driving speeds, I'm still only putting around the same amount of torque down on at the rear wheels as an equivalent gas engined truck.
The differences in torque with engines can, however make a big difference in driveability. Once in top gear my Ram never downshifts while cruising the highway, even up hills, etc where as a gas truck will downshift, etc to get the torque it needs to the rear wheels to maintain speed.
So, HP is HP and regardless of the engine type, torque output of the engine, etc equal HP engines will do the same work, it will just be a matter of how it is geared and what you have to do with the gears to maintain the output you need.
Contrary to popular belief, diesel engines are used in heavy equipment, not because they are higher torque engines, but because of economics. They last longer (lower RPM running, less longer term wear), more energy in equivalent amount of diesel fuel vs gas, better milage and less gear shifting while in use.
It would b e possible to put a 325 shaft HP turbine engine in my truck and do all the same pulling and highway driving with the same capabilities as with the diesel, but a turbine engine makes little torque, but has a huge RPM range (jet engines turn upwards of 150,000 RPM depending on size), but OMG, it would be a gearing nightmare to try to convert all that RPM to usable torque across a broad range of road speed. Turbines also don't spool up or down quickly, so while the "power" at the rear wheels could be made exactly the same, driving that thing would difficult at best, not to mention very costly since turbines are not particularly efficient on the fuel.
HP=torque x RPM divided by 5252.
Torque output at a drive point (wheels or PTO) is going to be a function of the gearing ratio since gearing is just round levers and we can trade RPM for more torque or vice versa using different gear ratios. Since the PTO should be running at 540 RPM, and we have the rated PTO HP, we can calculate the output torque at the PTO.
Mahindra rates the PTO HP on the 5035 gear models at 43HP, so our equation would be:
43HP=540 RPM X ??? lb-ft / 5252
5253 X 43 / 540
225836 / 540
418.12 lb-ft of torque at the PTO on those Mahindra 5035's.
Engine torque is really irrelevant since it's all going to run through various gearing which will make the trade offs in RPM and torque to get the desired speed at the drive point. That's why we rate engines in HP. It is a rating that indicates an engines ability to do work.
Diesels are high torque engines and they have to be in order to make equivalent HP to gas engines because they are RPM limited. Diesels just don't turn the higher RPM a gas engine does, but HP is still HP. So, you make a lot more torque, but you have to trade it off for RPM at the drive wheels (or PTO).
The 5.9L Cummins in my Dodge Ram makes 600 lb-ft of torque, way more than a 360cu-in gas engine, but it makes that torque at only 1600 RPM, so the transmission has be geared to trade off a lot of that torque for RPM at the rear wheels to reach highway speeds. It's a torque beast, but it's still only rated at 325 HP because of the low RPMs. In other words, due to the gearing, at normal driving speeds, I'm still only putting around the same amount of torque down on at the rear wheels as an equivalent gas engined truck.
The differences in torque with engines can, however make a big difference in driveability. Once in top gear my Ram never downshifts while cruising the highway, even up hills, etc where as a gas truck will downshift, etc to get the torque it needs to the rear wheels to maintain speed.
So, HP is HP and regardless of the engine type, torque output of the engine, etc equal HP engines will do the same work, it will just be a matter of how it is geared and what you have to do with the gears to maintain the output you need.
Contrary to popular belief, diesel engines are used in heavy equipment, not because they are higher torque engines, but because of economics. They last longer (lower RPM running, less longer term wear), more energy in equivalent amount of diesel fuel vs gas, better milage and less gear shifting while in use.
It would b e possible to put a 325 shaft HP turbine engine in my truck and do all the same pulling and highway driving with the same capabilities as with the diesel, but a turbine engine makes little torque, but has a huge RPM range (jet engines turn upwards of 150,000 RPM depending on size), but OMG, it would be a gearing nightmare to try to convert all that RPM to usable torque across a broad range of road speed. Turbines also don't spool up or down quickly, so while the "power" at the rear wheels could be made exactly the same, driving that thing would difficult at best, not to mention very costly since turbines are not particularly efficient on the fuel.
