better fuel consumption gear or hst ?

[wade simpson]

I've read many threads hear about the proper use of hst and it seems that an operator should keep the revs around 2000 or higher to get proper operation of hydro pump.

I have a gear tractor (ck20s) and very rarely go past 1800. For just general moving around I keep it around 1500. When working the fel or towing something heavy I will rev it until the engine sounds comfortable, generally between 1500 and 2000.

I've found a tank of fuel lasts me around 20 hrs. I just hit fifty hrs and have only put 20 dollars(cdn) in it. I generally leave it idling if I get off to do something that will take less than 20 mins or so.

As it wasn't broken in I kept the revs low but I found I didn't need to go beyond 2000 anyway.

I'm curious if HST use more fuel?

 

[SpringHollow]

If you do a lot of work that does not require major HP, a hydrostatic will use more fuel. Amazing what you can do with a geared tractor at low rpm. I saw a definite fuel increase with hydrostatic.

Ken

 

[radman1]

HST should use more fuel. More inefficiency due to the heat produced by HST which is wasted energy. Probably only noticeable under heavy load. However, if the HST is doing more work because of greater operator efficiency in a shorter period of time, then the HST could be more efficient. For example, mowing could require many stops, back up, turn ect. This can probably be done quicker with a HST and could overall save fuel compared to gear.

 

[wade simpson]

Good point. I've never operated an hst so I don't know if they work faster personally but it sounds right for the long time frame. I wonder if the gear operating at lower revs balances the operator efficiency?

 

[wade simpson]

That doesn't sound right. The engine operates more efficiently at peak torque but higher revs will always use more fuel. The lowest fuel use is at idle.

 

[radman1]

That doesn't sound right. The engine operates more efficiently at peak torque but higher revs will always use more fuel. The lowest fuel use is at idle.

You are correct. I believe K7LN is probably referring to optimum operating rpm with load on engine and fuel efficiency.

 

[wade simpson]

That sounds right. I think both of your points are good. If the tractor is able to do the same amount of work quicker it should ultimately use less fuel. I wonder if that's how it works out in the real world tho.

Hopefully some people that routinely operate both will have more insight.

 

[oldnslo]

This kind of like comparing a manual transmission to an automatic in cars and trucks. There are so many variables that no one system is ging to be better for all conditions.

Examples:
Mowing a flat lawn the HST is doing very little work while the PTO is absorbing the majority of the power. With lots of obstacles and turns you would probably finish mowing sooner with the HST so in theory the fuel consumption would be less.

Pulling a subsoiler which requires majority of the engine power be transfered through the tranny (gear or HST). In this case the gear would win since it is more effiecient unless there is no one gear that will keep the tractor under load. I.e. 5th gear it won't pull the subsoiler and 4th gear it won't make it work. Then the HST might be a better choice since you can match ground speed to load demand infinitely.

Roy

 

[SpringHollow]

It really comes down to what you are doing and for how long. Lots of low speed/idle, then the gear tractor will use less fuel. For everyone except a farmer, i doubt fuel consumption would be much of a consideration.

Ken

 

[wade simpson]

Like the name oldnslo, just how I feel

I can personally make a comparasion between auto and man cars/trucks. Manuals, in my observation, always use less gas in normal operation. However, a guy told me that his new dodge truck had a 5 speed auto, I've never had a 5 spd auto and that may make some difference but I still think the manual would use less gas.

I don't know if a hydro in a tractor is comparable to an auto in a truck tho.