Case Colt Ingersoll Tractors banner
1 - 20 of 24 Posts

·
Registered
Joined
·
2,125 Posts
Discussion Starter · #1 ·
1. Every forum dealing with I.C. engines has had lengthy discussions involving the definition of hp vs. torque.
2. I am not trying to revive that question. ( no equations please)
3.In the most simple terms my understanding of this arrives at, torque is a rotational force that does "work" . Horsepower is the rate (or speed) at which this "work" can be done.
4. Is it possible to arrive at an analogy of hp/tq vs hyd psi/gpm?
5. My thought is that hyd psi equals torque and flow (gpm) equates to hp.
6. I may have # 5 completely reversed due to the fact that I`m a moron.
7. Or am I missing the fact that it boils down to the external hp that`s turning the pump
8. I will get up early and don my flamesuit in eager anticipation of your answers.

signed:
Curious George the Monkey

EDIT: it`s raining so %& hard that Loch Ness is forming around my house. Can`t remember a spring this "damp"
 

·
Registered
Joined
·
270 Posts
Actually, not so bad-but a little off.

Hydraulics have a direct analogy in direct current electrical circuits. PSI is equal to voltage, flow/GPM is current, which is the rate of units of electricity (measured in coulombs) per second, expressed in amps. Obviously, restrictions such as an orifice or motor will serve as resistance.

Torque is force. Horsepower is power, which is how fast force/torque can be applied.

Volts times amps equals watts, which is also a unit measure of power-which can be translated into horsepower if you wish.

My shorts do not burn.
 

·
Registered
Joined
·
1,383 Posts
Couldnt help but post this equation.

Hydraulic Horsepower = (FLOW (gallons per minute) X PRESSURE (psi)) / 1714.3

Same can be done for calculating the horsepower required to drive a pump at the flow and pressure you want. These are not the most efficient machines around but very versatile (as compared to the typical direct mechanical drive) and variable speed is pretty awsome as well. Pump guy I know assume only 60% efficiency.
 

·
Banned
Joined
·
12,618 Posts
Rockdog said:
Couldnt help but post this equation.

Hydraulic Horsepower = (FLOW (gallons per minute) X PRESSURE (psi)) / 1714.3

Same can be done for calculating the horsepower required to drive a pump at the flow and pressure you want. These are not the most efficient machines around but very versatile (as compared to the typical direct mechanical drive) and variable speed is pretty awsome as well. Pump guy I know assume only 60% efficiency.
The gasoline engine and drive train in the family car isn't very efficient either. The engine generates quite a bit of heat that must be radiated to the air. It takes horsepower to spin alternators, oil pumps, distributors, water pumps, cooling fans, power steering pumps and air conditioning pumps but we accept all of those things in exchange for what they do. Some of them give us creature comforts while others are necessary for the engine to keep running.

The same holds true when it comes to the Case patented Hydriv system. No..... it isn't all that efficient but so what? A hydrostatic pump is a lot more efficient but it's also a lot more expensive to replace and I don't know of any true hydro pump that is capable of delivering a constant 10 GPM at pressures up to 2300 PSI when called upon to do so. So whether the efficiency is 80 percent or 60 percent, it doesn't matter to most owners because they are very happy with how their tractors work for them.

There isn't another brand of garden tractor that will do what a Case, Colt or Ingersoll will do.
 

·
Registered
Joined
·
1,383 Posts
Tom - Well, I dont follow the engine and accessaries angle but modern automotive drivetrains are pretty efficient - 93% or even more. Similar system have been used in heavy equipment (Ag included) for decades. But the things that make them efficient are the same things that make them less desirable than the hydraulic drive system used on these tractors. And I agree that i could care less if it cost me 4 dollars more to mow my grass.

Point of my last post was that you can calculate the hydraulic HP available and how much is needed to provide that HP - just dont be dissapointed by the results.
 

·
Registered
Joined
·
2,125 Posts
Discussion Starter · #6 ·
I must be missing something.

^ 93% ? you lose 15% to friction just getting from the crankshaft to the driving wheels

And the heat energy lost is enormous, those BTU`s don`t propel the vehicle.

I repect your background but I must politely disagree
 

·
Registered
Joined
·
1,383 Posts
I'm just going by what has been measured on dynomometers in my experience. The overall system efficiency changes depending on the system you use but in this case I was thinking more along the lines of crankshaft to input of the final drive. The efficiency of the rear axle wouldnt really change if it were driven from the output shaft of a hyd motor or a propellor shaft. So overall they can be less but apples to apples it is very more than fair to say hydraulic drive is less efficient 90% of the time than a typical mechanical drive.
 

·
Registered
Joined
·
2,125 Posts
Discussion Starter · #8 ·
Rockdog said:
it is very more than fair to say hydraulic drive is less efficient 90% of the time than a typical mechanical drive.
^ I agree 100% with that statement :wave:
On power train losses, my exp has been:
4.6 L Mustang GT`s ( mines an `07) are rated 300hp by the S.A.E. NET method of all acc drives and stock manifolds installed etc. Output is then measured at the crankshaft
When you strap the car to the dyno, you obtain an avg of 255- 262 rwhp.
YMMV
 

·
Registered
Joined
·
1,383 Posts
99FLHR - Like I said, i wasnt including the engine and accessories. That is not considered driveline/drivetrain. That is powertrain. Big Difference.

So, transmission that is 7% drag loss, axle at 7%, t-case,....add everything up and you end up with a total loss range you've described.

So if you look at a simple mechanical coupling vs. a hydraulic pump and motor there's a huge drop in efficiency. But there are benefits to the hydraulic set-up as well but you wont see them when you're just mowing grass (you'll see the opposite cause thats probably where the biggest seperation of the two exists).
 

·
Banned
Joined
·
12,618 Posts
For the sake of discussion, let's say that it takes 2HP to propel the tractor, 2 HP to spin the mower deck and 1 HP to run the alternator. Theoretically, you need 5 HP to meet those needs. However, there is nothing available to cover the various losses or the eventual decrease in HP due to engine wear and tear. You solve the problem by putting in a 10 HP motor.. Theoretically, the 10 HP motor won't make the tractor go faster or the deck blades spin faster but that engine will have enough residual power to cover the driveline losses plus the deterioration losses due to wear and tear. Even if the true engine HP falls from 10 HP to 8 HP, the tractor will likely behave much like it did when it was new.

Efficiency is displaced by the practicality of building a tractor that will give excellent service for many years and still be able to be rebuilt for a modest cost so that it can continue to give excellent service for many more years. Efficiency often comes at a very high price but the question is whether it is truly needed when a less efficient system will deliver satisfactory results. Do you see anybody bitching about their Colt, Case or Ingersoll tractors? That's the only test that truly matters.
 

·
Registered
Joined
·
1,383 Posts
The engine size comes into play under heavy load and the governor kicks in to maintaing engine rpm. A 'smaller' engine will reach full throttle at a lower load than a larger one. This means an operator would need to reduce the load on the engine in order to maintain RPM. The PTO side load isnt really operator controllable (other than digitally) but the drive motor flow is. Therefore the operator would need to slow the machine ground speed in order to maintain engine rpm. The larger engine could maintain engine speed until such time full throttle load is achieved. As long as the load on niether machine exceeds full throttle the speeds would remain the same.

And, no, efficiency doest matter very much when your talking garden tractors. But it is noticable. The big benefits over mechanical system I see is excellent inching capabilities and infinitley variable drive motor flow so the operator can maintain engine rpm in its torque range. Cant really do that very well with mechancial system (kind of hard to shift a garden tractor under load while plowing).

As far as price or cost to rebuild goes...I dont know what would be cheaper.
 

·
Banned
Joined
·
12,618 Posts
Without question, engine size comes into play. The old hot rod adage that there's no substitute for cubic inches holds true with garden tractors too. The Onan B48 is of larger displacement than most of the modern V-twins but it's also thirstier. On a Case or Ingersoll tractor, you can have two PTO's in operation at the same time. The mechanical PTO on the front of the engine can be spinning up a 60 inch deck while the rear PTO can be spinning up the vacuum needed to bag the material spit out by the deck.

The engine is being asked to supply HP for the deck, the vac, the alternator, the cooling fan and the drive motor that propels the tractor. If the property has steep hills to mow, then the load on the engine increases as a result of having to climb those grades. If an area of thick, damp lawn is encountered, then the load is increased again. But as you say, the operator can instantly compensate for those added loads by pulling the travel lever back to slow the ground speed so that optimal engine RPM is maintained. That's the beauty of having fluid drive of either hydraulic or hydrostatic as opposed to a gear box that requires the tractor to be stopped in order to select a different ratio.

One advantage to the Case Hydriv system is that the pump and the drive motor are two totally separate items that can be quickly unbolted from the tractor by just about anyone with a decent set of tools and a rudimentary ability to perform mechanical repairs. A new pump can be had for about $200.00 and drive motors rarely need replacement. If you have a drive motor problem, then it can often be cured by purchasing a used drive motor for less than $100.00 OR... you can have a local hydraulics shop rebuild your drive motor for a fairly reasonable price. If you own a tractor with hydrostatic drive, you could be faced with one of two systems. The higher end systems use a separate hydrostatic pump just as Case/Ingersoll uses a separate hydraulic pump. The difference here is that you will have to pay a minimum of $700.00 for a new pump which is 3 1/2 times the price of a Case pump and it could rise to as much as $1200.00.

More likely than not, your tractor will not have a separate pump. Instead, it will have a trans-axle UNIT with the hydro pump, drive motor, trans-axle gears and axle shafts inside an enclosed housing. In order to service the pump, then entire trans-axle must be removed from the tractor and split open. This is not a task for the average guy. Cleanliness is paramount. The lint off of a rag is enough to cause a problem with the re-assembled unit. Every day on this forum, we discuss the prices being asked by Sellers on Craigslist and elsewhere. Having a Pro shop rebuild the hydro axle in your GT will likely cost you more money than what a nice 448 with a deck will cost.

There is no question that hydrostatic drives are far more efficient than hydraulic drive. And you are right that efficiency is noticeable but it is most noticeable when it comes to how much money is left in your wallet.
 

·
Registered
Joined
·
270 Posts
So anyway, I realized today that I didn't really answer the original question- and that is...

Torque is roughly equivalent to pressure/PSI in a hydraulic system. The "motion" part to get to horsepower is flow.

Efficiency? Well, I do notice that the 448 uses a good amount of fuel, especially since my wife has decided to mow an extra field more regularly. Still, not too big a deal in view of the cost to replace the good old thing.
 

·
Registered
Joined
·
2,125 Posts
Discussion Starter · #14 ·
xfolkboat said:
So anyway, I realized today that I didn't really answer the original question- and that is...

Torque is roughly equivalent to pressure/PSI in a hydraulic system. The "motion" part to get to horsepower is flow.
I was somewhat hesitant to bring that up. You turned it into electricity, ( good analogy) which I understand even more poorly than hydraulics
Thank you

By the way, I was referring to me being flamed, not the responder :wave:
 
1 - 20 of 24 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top