[AT] Add-on hydraulics and power steering?

Cecil Bearden crbearden at copper.net
Tue Apr 24 03:57:56 PDT 2007


Dudley:
Good point. 
When I size a pump for a utility tractor, I use a larger pump so that I 
get a good speed on the loader at just above idle.  Also when using the 
bucket or loader, we don't have to have full power at the same time.  
This normally results in welding on the loader frame.  We use our 
loaders so much for positioning machinery and working on buildings and 
equipment and loading hay.  I think the last time we had a load of dirt 
or gravel in the bucket was about 2 months ago.

I am putting up a building for a neighbor 65 x 150 and he has a skid 
loader with a boom that raises 20 feet.  When we get to setting our 
trusses up. I am going to use the John Deere 4010 with the Farmhand 
loader.  I don't trust a skid loader at that height..  we are building 
our trusses..

Dudley Rupert wrote:
> John,
>
> You asked in your' email of last Saturday, "Can a pump be too big to run
> such a system?"  The short answer is yes but I thought it would be
> interesting to write down some of the trade offs that are made when deciding
> pump size.
>
> Let's take an example:
> Let's say we had a Ford 8N engine on a stand and that it developed 25 HP at
> 2,000 RPM.
> Let's say further that we wanted to use all the output of this engine to
> drive a single hydraulic pump that would provide 1,500 PSI pressure when
> under full load.
> Question:  How big of a pump could we use without stalling the engine?
>
> Answer: The formula for determining the HP required to drive a hydraulic
> pump is:
> HP = GPM * PSI / 1714 or
> GPM = 1714 * HP / PSI so in this case
> GPM = 1714 * 25 / 1500 or
> ~ 28 GPM
>
> Now let's take another example:
> Let's say we had a Ford 8N tractor with a loader and we want to determine
> how big of a pump to buy.
> We know we don't want to use a 28 GPM pump as that would leave no engine
> power to drive the tractor when operating the loader under full load.
> So, let's say we are willing to give up 25 percent of the engine power to
> drive the pump which leaves ~ 19 HP to drive the tractor.
>
> So, GPM = 1714 * (0.25 * 25) / 1500 = ~ 7 GPM
>
> Interestingly I have three loaders that I think are all from the fifties: a
> Ford, a Bush Hog and a Davis.  Two have Vickers pumps and one has a Borg.
> The capacities of these old pumps range from 5 to 8 GPM at nominal tractor
> speeds ... hum; maybe my 25 percent assumption was not too far off.
>
> On a related note I finished installing the Davis loader on a Ferguson 35
> last week.  The Vickers pump on the Davis was a 5 GPM pump.  I think the
> Ferggy 35 has around 33 HP.  I decided I wanted a bigger pump and that the
> 35 has sufficient power so I installed an Eaton pump with a capacity of ~11
> GPM (I have the system pressure relief valve set at 1500 PSI).
>
> So, this 11 GPM pump, when under load, would require
> HP = 11 * 1500 / 1714 or
> ~9 HP which leaves ~24 horses for the tractor.
>
> So far I am pleased with this configuration (as in I like the up & down and
> bucket dump speed) although I haven't yet really operated the loader in a
> pile of heavy debris where tractor power - or lack of - will come into play.
>
> I think these examples illustrate that within some broad parameters
> determining pump size can be as much a matter of personal liking as it is an
> exact science.
>
> I hope this helped ... some at least.
>
> Dudley
> Snohomish, Washington
>
>
>
> -----Original Message-----
> From: at-bounces at lists.antique-tractor.com
> [mailto:at-bounces at lists.antique-tractor.com]On Behalf Of Dudley Rupert
> Sent: Sunday, April 22, 2007 10:09 AM
> To: Antique tractor email discussion group
> Subject: Re: [AT] Add-on hydraulics and power steering?
>
> John,
>
> The back fifteen or twenty pages of the 2004 Hydraulic Parts Components
> catalogue from Force America contains a good tutorial on hydraulics.  Their
> website is www.forceamerica.com and their number is 888-99FORCE.  I don't
> have their latest catalogue but I would guess that it would also include
> this tutorial information.
>
> A hydraulic pump can be used for both power steering and another application
> like say a loader.  However, to maintain the performance of the power
> steering system while both turning and using the loader requires a Flow
> Divider (or something that works like it).
>
> A Flow Divider is like a Y valve with one input (which is connected to the
> pump output) and two outputs.  One output is connected to the power steering
> and the other to the loader.  The function of the Flow Divider is to ensure
> that a minimum flow of hydraulic fluid is always diverted to one of its'
> output ports.  Let's say power steering needs a minimum of 3 GPM to function
> properly (I have no idea if this is anywhere near correct).  Then,
> installing a Flow Divider with a 3 GPM rating on one of its' output ports
> for the power steering could be used.  The loader, which is connected to the
> other Flow Divider output port, will then only get what the pump puts out in
> excess of 3 GPM.
>
> FWIW - I have seen several tractors with power steering that used a Flow
> Divider but not also with a loader - usually just a function that required a
> single actuator like an add-on 3-pt hitch.  For a loader application I think
> I would want dedicated pumps for both the loader and power steering, as I
> wouldn't want the loader performance to suffer any while turning.
>
> Dudley
> Snohomish, Washington
>
>
>
> -----Original Message-----
> From: at-bounces at lists.antique-tractor.com
> [mailto:at-bounces at lists.antique-tractor.com]On Behalf Of Larry D Goss
> Sent: Sunday, April 22, 2007 7:18 AM
> To: Antique tractor email discussion group
> Subject: Re: [AT] Add-on hydraulics and power steering?
>
> Are you sure the pump is turning the right way?  Some pumps have the
> pressure relief valve built into them and won't run backwards.
>
> Larry
>
> ----- Original Message -----
> From: "John Wilkens" <jwilkens at eoni.com>
> To: <at at lists.antique-tractor.com>
> Sent: Saturday, April 21, 2007 11:15 PM
> Subject: [AT] Add-on hydraulics and power steering?
>
>
>   
>> Anyone know of a good book on very basic practical application of
>> hydraulics and old tractors?  One specific is...can you use a front
>> or rear mount hydraulic pump that is being used to run a loader (etc)
>> to run an add-on power steering unit also?  What capacity pump would
>> be required?  What kind of plumbing and fixtures would be
>> needed?      Also, can a pump be too big to run such a system.    I
>> tried to run a wood splitter off of a large BeeGee pump hooked up to
>> the belt pulley shaft on an AC WC tractor (came off of a Cat) but
>> about all it did was heat up the oil and stall the tractor.  One guy
>> told me the pump was "just too big."  ???
>>
>>                    In the wide-open spaces of NE Oregon
>>
>>
>>
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>>     
>
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