PTO Pump

[Dougster]

I timed my 6520 this morning after a quick warm up and at 1700 rpm, it rasied the bucket right at 9 seconds. At 2000 rpm, it raised the bucket right at 8 seconds. I did this 3 times and got the same results. I used my watch. I didn't look at the bucket at all, but felt the bucket hitting the top "stop".

Oh Lordy Lordy! This just adds to the mystery! It still could be either pump! I give up until we get some photos!!!

Dougster

 

[bindian]

Brandi, is there any initial jerkiness as you raise your loader the 1st time after sitting overnite. if so you have a suction side air leak. If not you have the 11.9 pump or, much less likely, a pressure side leak to the sump return or PB line when you are raising the loader.
larry

Larry,
I don't remember any jerkiness. I will see in the morning. Remember I do have the 6520. According to my Ops Manual loader times, everything is fine.
hugs, Brandi

 

[bindian]

Oh Lordy Lordy! This just adds to the mystery! It still could be either pump! I give up until we get some photos!!!

Dougster

Dougster,
You want photos??? I have a lot oif photos of my dog. How many do you want?
I guess I can take the side panels off and see about a photo session. But not Wednesday. It will have to be sometime Friday.
hugs, Brandi

 

[Dougster]

Dougster, You want photos??? I have a lot oif photos of my dog. How many do you want? I guess I can take the side panels off and see about a photo session. But not Wednesday. It will have to be sometime Friday.
hugs, Brandi

Doggies are great!!! Let's see them!

Seriously, I guess I shouldn't assume that you can see the hydraulic pump on other tractors from the outside like you can on mine:

Admittedly, for my own selfish reasons relating to this backhoe performance issue, I'd just like to see this 7520 vs. 6520 pump mystery solved once and for all.

Dougster

 

[Willman]

Just to put my 2 cents in this pump conversation....
Last week I was discussing with my local dealer about what pump is in my 2004 4110 and if the newer pump would be a direct replacment.
He had no idea.
I too would like that 10-15 % more power for the 509 BH.
It just seems to have a slight lack of power now that I really know how to use the BH.

 

[DavesTractor]

Just to put my 2 cents in this pump conversation....
Last week I was discussing with my local dealer about what pump is in my 2004 4110 and if the newer pump would be a direct replacment.
He had no idea.
I too would like that 10-15 % more power for the 509 BH.
It just seems to have a slight lack of power now that I really know how to use the BH.

More volume gives you more speed, but not more power. Higher pressure gives more power.

 

[Dougster]

Just to put my 2 cents in this pump conversation.... Last week I was discussing with my local dealer about what pump is in my 2004 4110 and if the newer pump would be a direct replacment. He had no idea. I too would like that 10-15 % more power for the 509 BH. It just seems to have a slight lack of power now that I really know how to use the BH.

Hi Will - As mentioned earlier, I am not entirely sure that we don't already have the alleged "larger" pump. The fact is that I think they are playing games... perhaps unintentionally and even unknowningly... with the advertised flow hydraulic rating of the 4110.

Here is what I know and don't know. Perhaps someone can fill in some of the gaps: The pump on my October 2004 production Model 4110 is a Joyang Hydrotech Co., Ltd. Model F21 Double Type Pump (feeds hydraulic system and steering through different sections). The hydraulic system feed section is rated at 14.0 cc/pump revolution while the steering is rated at 6.5 cc/pump revolution. Those are theoretical ratings at 100% volumetric efficiency. The pump is good up to 3,000 pump RPM. That much is clear.

Beyond that, things get murky. At various times, Mahindra has rated the 4110's hydraulic system flow at 2,700 engine RPM and at 2,500 engine RPM. At times they have used a conservatively assumed 91% volumetric efficiency and at other times... perhaps now? ...something higher. According to Joyang, the volumetric efficiency of my main pump section, apparently brand new, varies between about 96.5% and 99.0% depending mainly on oil temperature. The volumetric efficiency of the steering pump section, brand new, is slightly lower at between about 92.0% and 99.0%. It is unclear if there is a drive ratio... engine RPM vs. pump RPM... although one can make a good case based on the numbers that it is 1:1. Still, I have been unable to confirm this critical piece of data so far.

Historically, the 3510 appears to have always had one pump size down (in both sections) from the 4110 to save a little power... or at least that appears to have been the original design intent. It is unclear if this design criteria changed over the years intentionally or simply by accident... either physically or just on paper. For years, the published ratings were the same for the main hydraulic pump section for both machines... but different for the steering pump... a very unlikely real world situation if Mahindra had chosen to standardize on one pump. Now, of course, both main and steering section published flow ratings are different for the two machines.

There is other evidence and I could go on, but you get the idea. Based on the actual pump I've got and different operating assumptions and roundoffs, you can make a very good case that my late-2004 already has a 9.5 GPM pump. Or not.

I forgot to check the pumps on the new 2006 and 2007 4110's that I found down at different dealerships in MA and CT. My aging mind was on other tasks those days and I didn't have my camera with me anyway. Never did find a new 3510 to check... and that input is critical to my theory.

This backhoe performance & PTO pump discussion has sparked my interest again... so next time I promise not to be so forgetful. When I learn more, I will publish my results!

Dougster

 

[Dougster]

More volume gives you more speed, but not more power. Higher pressure gives more power.

Hi Dave - Certainly in a static, controls-free, hydraulic model that would be the case... but do we really have a true static model here? I remember asking the original selling dealer (i.e., the owner) about this in regard to possibly buying the PTO pump and he talked about the big increase in speed but also talked about a roughly 10% increase in effective digging power.

I doubt he was an MIT hydraulics professor, but he certainly had plenty of BH seat time & PTO pump-installing experience, so I took that to mean a bit more seat of the pants power... or maybe just more useful power. Even on my 4110 (without a PTO pump)... it seems to me that I can exert a helluva lot more force on an object with the RPMs at 2500 than at 2000. It seems like it's more than just speed. It seems like there's more digging power.

Is there anything to this? Or are we just wishing or imagining it?

Dougster

 

[SPYDERLK]

More volume gives you more speed, but not more power. Higher pressure gives more power.

power is speed times force. So it will have more power even tho no more force at same P with higher flow.

larry

 

[Dougster]

power is speed times force. So it will have more power even tho no more force at same P with higher flow.
larry

A good point. Dave probably meant: More volume gives you more speed, but not more digging force. Higher pressure gives more digging force.

I should have been more careful with terms as well.

Dougster