[AT] 8.9 liter Perkins

[John Maddock]

I note that the 1155 was built between 1973 to 78.  As I understand, MF
lower horsepower tractors of a similar age (and certainly the 100 series)
had three pumps: the Scotch yoke piston pump to drive the 3 pt lift; an
internal  gear pump driven by a gear off the pto shaft to supply external
services, a second gear pump piggy-backed on the first gear pump to supply
Multi-power and pto clutch packs if fitted. A pressure maintaining valve
was fitted on the line to the Multi-power clutch to maintain the pressure
for the PTO clutch when Multi-power was set to "low", the oil being dumped
in that state.

The medium horsepower tractors had a fourth (gear) pump with its own oil
supply, driven from the engine for power steering.

 JV
> James,
>
> I agree that using relief valves to regulate pressure or flow is not a
> good thing, especially with a fixed displacement pump. I have seen it done
> before, but agree that it generally just makes heat. It might work with
> open center valves where there is no pressure in the circuit until a valve
> is actuated. With closed center valves it is just a heat generator that
> wears out relief valves and hydraulic fluid.
>
> I have trouble believing a tractor manufacturer would design a system like
> this. I think a more probable design would be a 3 stage pump or multiple
> pumps. If they were pressure compensated pumps it would be a great
> circuit.
>
> Thanks
> Dennis
>
>
> Sent from my iPad
>
>> On Feb 23, 2019, at 3:52 PM, James Peck <jamesgpeck at hotmail.com> wrote:
>>
>> Pressure Relief Valves used to regulate pressure on fixed displacement
>> pump systems waste energy by relieving pressurized fluid back to tank.
>> In one mobile equipment project, we used flow over a pressure relief
>> valve to heat hydraulic fluid to the minimum temperature needed to allow
>> the main pumps to operate.
>>
>> Three pressure relief valves may generate the heat Cecil was mentioning.
>>
>> Maybe one of us can dig up a hydraulic schematic for an MF 1155.
>>
>> With pressure compensating pumps you only need to use a pressure relief
>> valve to set the pilot pressure to the pump. This wastes much less
>> energy as you only have pilot flow going back to tank.
>>
>> https://www.hydraulicspneumatics.com/other-technologies/book-2-chapter-18-pressure-relief-valves
>>
>> [Larry Goss] It's not uncommon to find multiple pressures on various
>> portions of a hydraulic system.  The easy way to do it is just to "daisy
>> chain"  the control valves with lower and lower operating pressures on
>> the relief valves. The last system simply dumps back into the reservoir.
>>
>> [ James Peck]  3 pressure systems? Does that mean three hydraulic pumps?
>> Where were they all located?
>>
>> [Cecil Bearden]The high pressure 3000+ psi for lift, the 1500+ for
>> steering and then the  +/-500 psi for multi power clutches controls and
>> PTO controls.   We had one for several years.  MF left out a snap ring
>> in the PTO clutch and it did not work for the original owner.  It was 6
>> years old when we bought it.  We had to pull the cab and the top deck to
>> find the problem.  A few years later my Dad put the wrong oil in the
>> hydraulics and the multi power and PTO started to have problems.   Later
>> found the O-rings were going bad and to repair meant nearly a complete
>> disassembly of the tractor.   It went to Mexico.
>>
>> A few years later we bought a 7030 Allis Chalmers to replace that
>> tractor.  The Allis has the same features and a few more, but only one
>> pressure system.   After I sealed off the dash to get the Air
>> conditioner working it was  very good tractor and very simple. The
>> problem with it now is a large diameter O-ring in the main clutch is
>> going bad.  It means a split of the tractor, but can be repaired for a 2
>> day job...
>>
>> I really liked that 1155 Massey, but it developed so many problems and
>> used so much fuel it was a pain.  The V-8 has to be kept running above
>> 1900 rpm or it gets hot...    Our 1155 was built while Massey was having
>> a lot of problems.  I grew up in a MF dealership, and I bled red & grey,
>> had red & grey underwear too.  But that 1155 we had just ruined Massey
>> as far as I am concerned.   They got more complicated than necessary.
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