Tractor Sizing What comes into play when choosing HP?

   / What comes into play when choosing HP? #1  

dustinfox

Gold Member
Joined
Sep 26, 2011
Messages
433
Location
New Hampshire
Tractor
Kioti CK35 HST
I am hearing that the engine HP rating is an important consideration for operating attachments but for loader and backhoe operations it is the hydrolics that do all the work. How true is this? For example, when choosing between a 25HP tractor and a 35HP tractor, if I do not foresee using a PTO for anything, and all else being equal (exactly the same tractor but with different engine HP) will the 25HP perform as well as the 35HP?
 
   / What comes into play when choosing HP? #2  
The pump determines the power of the hydraulic attachments. Many times, the OEM will offer a similar tractor in three different HP at 3 different price points, but may all use the same attachments and run off the same sized gpm pump. Be very sure.

On pto attachments, horse power is king and there's no real substitute.

In pulling or pushing, there's usually a limit of hp to effect results due to light weight and loss of traction, which is the holy grail.
 
   / What comes into play when choosing HP? #3  
The pump determines the power of the hydraulic attachments. Many times, the OEM will offer a similar tractor in three different HP at 3 different price points, but may all use the same attachments and run off the same sized gpm pump. Be very sure.

On pto attachments, horse power is king and there's no real substitute.

In pulling or pushing, there's usually a limit of hp to effect results due to light weight and loss of traction, which is the holy grail.

While this is true, you also need the HP to turn the pump while under a given load. ;) If the weight of the machine is capable of doing a certain task, then more HP will usually allow you to do that task faster.
 
   / What comes into play when choosing HP? #4  
In most cases, when using the hydraulic pumps on CUTS for a loader, backhoe, log splitter, etc, you are not using it while traveling. Or at least you are not pushing/pulling a significant load while dumping a loader for example. And for simple traveling while dumping, you won't notice a difference in speed, ground or dump. There may be a few chores that do muliple tasks whereby the pump performance could be affected. But for most users, I doubt this comprises a large portion of their work.

Also, it depends on the pump configuration. Some designs use one pump for several shared tasks, like power steering, implements, tranny. Other designs have mulitple pumps that split the tasks. Kioti's/BC's have 2 pumps. One for power steering, and one for everything else. In this way PS isn't compromised by loader work and visa versa.

The pump gpm limits operating speed, more so than hp. So, then a tractor that puts out say 7 gpm for implements does so without fully taxing all of the hp. Therefore, the same tractor with the same pump running the same implements at the same rpms will perform the same regardless of engine hp, as long as their is at least enough hp to run the pump at full gpm.

I do believe HST's are more geratly affected by pump gpm than gear tractors due to the nature of HST trannies requiring more of the gpm to function. Whereas the gear trannies mainly use hydro pressure for shifting/clutch/pressure plate engagement.
 
   / What comes into play when choosing HP? #5  
In most cases, when using the hydraulic pumps on CUTS for a loader, backhoe, log splitter, etc, you are not using it while traveling. Or at least you are not pushing/pulling a significant load while dumping a loader for example. And for simple traveling while dumping, you won't notice a difference in speed, ground or dump. There may be a few chores that do muliple tasks whereby the pump performance could be affected. But for most users, I doubt this comprises a large portion of their work.

Also, it depends on the pump configuration. Some designs use one pump for several shared tasks, like power steering, implements, tranny. Other designs have mulitple pumps that split the tasks. Kioti's/BC's have 2 pumps. One for power steering, and one for everything else. In this way PS isn't compromised by loader work and visa versa.

The pump gpm limits operating speed, more so than hp. So, then a tractor that puts out say 7 gpm for implements does so without fully taxing all of the hp. Therefore, the same tractor with the same pump running the same implements at the same rpms will perform the same regardless of engine hp, as long as their is at least enough hp to run the pump at full gpm.

I do believe HST's are more geratly affected by pump gpm than gear tractors due to the nature of HST trannies requiring more of the gpm to function. Whereas the gear trannies mainly use hydro pressure for shifting/clutch/pressure plate engagement.

The hp makes a HUGE difference when an HST is involved. Ask anyone that has operated a Kioti-BC27 and then operated a 35. Unless you are on flat ground only, there is a HUGE difference.
 
   / What comes into play when choosing HP? #6  
The hp makes a HUGE difference when an HST is involved. Ask anyone that has operated a Kioti-BC27 and then operated a 35. Unless you are on flat ground only, there is a HUGE difference.

Yes, I know all about the complaints about hp on the CK HSTs when traveling. They are heavy machines that can sap a lot of power, especially on inclines. That's one of the main reasons I opted for a gear. But, don't believe it affects loader/backhoe performance one bit, unless traveling while operating the loader or backhoe at the same time. So, in that light, the more hp the better they perform (all things considered). Transport wise, the hp does matter. However, the CKs have identical lift specs, pumps,flow specs, loader/backhoe sizes, and cycle times. From a purely loader/backhoe performance standpoint, users will not notice a difference between the three models when working them from a stand-still position. One won't lift any more than the other, nor cycle any faster.

I do agree that operating a pump driven implement takes hp, hp that could otherwise be applied to the drive train.
 
   / What comes into play when choosing HP? #7  
Dustin,
You also have to think about what you will use the tractor for. Being in New Hampshire do you have a long drive to plow or use a snow blower, flat or hills any logging? You can do almost anything with either size but it will take you longer with the lower HP. I have read on TBN many times that nobody ever wished they bought a smaller tractor. :)
 
   / What comes into play when choosing HP? #8  
Yes, I know all about the complaints about hp on the CK HSTs when traveling. They are heavy machines that can sap a lot of power, especially on inclines. That's one of the main reasons I opted for a gear. But, don't believe it affects loader/backhoe performance one bit, unless traveling while operating the loader or backhoe at the same time. So, in that light, the more hp the better they perform (all things considered). Transport wise, the hp does matter. However, the CKs have identical lift specs, pumps,flow specs, loader/backhoe sizes, and cycle times. From a purely loader/backhoe performance standpoint, users will not notice a difference between the three models when working them from a stand-still position. One won't lift any more than the other, nor cycle any faster.

I do agree that operating a pump driven implement takes hp, hp that could otherwise be applied to the drive train.

I agree that in most situations, at a stand still the HP is not going to be a big difference, but as soon as you start to move, especially with an HST trans and work the tractor, HP is a big factor.
 
   / What comes into play when choosing HP?
  • Thread Starter
#9  
Hmmm... I was going to get an HST so the wife could drive the tractor but now you've all got me thinking I should convince her she should learn to deal with a gear transmission.:confused:
 
   / What comes into play when choosing HP? #10  
Hmmm... I was going to get an HST so the wife could drive the tractor but now you've all got me thinking I should convince her she should learn to deal with a gear transmission.:confused:

Or just not let her play with your new toy:D

So far great advice has been given. I cannot really add to anything, just kinda sum it up.

IF the hydraulic specs/pump is the same, no difference sitting still.

Moving tractor, More HP will be noticable and allow you to do more work faster. BUT, faster doesnt mean it can do more. The smaller HP tractor will be able to do EVERYTHING the larger one will (not counting PRO stuff), it just may need to be done in a lower gear.

Example: I have a L3400 'bota. Where we cut wood, there is a BIG hill as soon as we pull out onto the road. With a trailer load (3/4-1cord) of wood, I can usually stay in 4H(gear tranny). But sometimes I do have to downshift. THIS is a case where HP runs out before traction. If I had gotten the L2800, I would probabally have to downshift far more often.

But when it comes to pulling other things offroad, the larger tractor may just allow you to do it a gear faster:thumbsup:
 
 
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