2 stage pump for loader

[J_J]

Here is the reason I ask.

My steering and lift uses a 3 GPM hyd pump capable of 3000 psi. It is slow, but functional. It runs off the fan belt.

I see the advantage as faster operating speed as to steering and lift with a light load.

The pump would run at high GPM up to 800 psi most of the time, and jump into the power mode when the shift psi is met.

How much of a load can the loader lift at say 800 psi, I don't know. I could set a work port relief set to 800 psi on it to determine the max lift.

What are your thoughts if any.

 

[mikehaugen]

Are you saying you are thinking of replacing your current pump with a 2-stage?

Wouldn't the pump be constantly shifting, especially steering on uneven terrain? Also, I imagine, unless you are very delicate with the controls, even an empty loader would have a enough surge pressure when you first try to move the loader joystick.

I am not real familiar with 2 stage pumps, but once they shift doesn't the pressure have to drop to near zero for it to shift back to low pressure?

 

[J_J]

I thought I might check out the concept.

I believe the shift point is automatic. Both hi and low sections are running at the start, and when the set point is met, the hi section kicks out for power mode

On level ground, I don't see a lot of pressure on the steering.

My PT has a steering cyl on each of the front half for steering.

I was hoping that someone has done this before and had experience to share.

 

[jaotguy]

my BH / FEL uses a 2 stage ( wood splitter style ) belt driven ... fast at light loads , only when digging hard stuff ( or hooking a root/ rock) does it kick into Hi pressure ... the FEL never makes it to HI , even when loaded .... the HI / LOW is adjustable at the pump ( but I've never had to touch it )

but it's not a hydro trans , nor pwr steering ....

 

[puckgrinder85]

It definitely sounds like a good idea on paper. Maybe more industrial applications use it? Seems like it would save cycle time and some fuel. I don't like having to run my tractor up so high as to get decent flow and fast loader movments even though the load might be quite minimal at times.

For your 800psi, couldn't you just divide it up, I mean your loader must lift XXXX lbs at XXXX psi right? Wouldn't the lift capacity be pretty linear to pressure all things being equal.?

 

[timbatrader]

I have an old forklift at work that has a set up with a two stage pump the high pressure side feeds the power steering the low pressure feeds everything else I were told it was set this way so the steering always gets pressure regardless of what other valves are operating. For what you are after I would think just a larger pump would work better and be cheaper than a two stage. The main advantage with a two stage is a high flow with small horsepower I would guess you have plenty of horsepower for a decent sized pump

 

[SIMassey]

Here is the reason I ask.

My steering and lift uses a 3 GPM hyd pump capable of 3000 psi. It is slow, but functional. It runs off the fan belt.

I see the advantage as faster operating speed as to steering and lift with a light load.

The pump would run at high GPM up to 800 psi most of the time, and jump into the power mode when the shift psi is met.n

How much of a load can the loader lift at say 800 psi, I don't know. I could set a work port relief set to 800 psi on it to determine the max lift.

What are your thoughts if any.

I would think you need to run a priority valve directing the first few gallons to the steering circuit relieved to maybe 600 psi. Many steering systems run low pressure I am told. The only problem I see is the pump output at high pressure. It may not be enough to even supply the the steering adequately. Changed an Oliver super 55 power steering from a generator mounted power steering pump to run off the front pump for the loader. Added the priority valve but didn't add a relief and started blowing power steering hoses. After adding the relief, have not had any problems since and operates great.

 

[J_J]

The fluid from my current pump goes to the steering first and then to the loader.

The steering has priority, and will stop the lift if steering hard. When finish steering, the fluid bypasses to the loader.

I should do some pressure testing in normal conditions and then under a load to see if the idea is even feasible. .

You should always add a relief in open center hyd systems.

 

[SIMassey]

Here is the reason I ask.

My steering and lift uses a 3 GPM hyd pump capable of 3000 psi. It is slow, but functional. It runs off the fan belt.

I see the advantage as faster operating speed as to steering and lift with a light load.

The pump would run at high GPM up to 800 psi most of the time, and jump into the power mode when the shift psi is met.

How much of a load can the loader lift at say 800 psi, I don't know. I could set a work port relief set to 800 psi on it to determine the max lift.

What are your thoughts if any.

Current listing for power trac 1445 lists pto at 15 gpm. Yours old and different?

 

[J_J]

MY PT-1445 is an early 90's model, and has a 45 HP gas engine with radiator.

I have three pumps, a VSP pump for the drive train, a 13 GPM PTO pump, and a 3 GPM pump for the steering and lift.

Here is my steering and lift pump.

 

[jaotguy]

45 HP ... might as well go with a larger pump ....

 

[J_J]

Perhaps, but the other two pumps were selected to match the HP.

Another restriction is the fan belt ability to handle the load imposed by the larger pump at max pressure.

 

[jaotguy]

well then .. it's settled , a two stage pump it is ... ( I guess ) .. a 5 hp rated one should be fine on the one fan belt ... set to 600-800 low side ...

 

[SIMassey]

MY PT-1445 is an early 90's model, and has a 45 HP gas engine with radiator.

I have three pumps, a VSP pump for the drive train, a 13 GPM PTO pump, and a 3 GPM pump for the steering and lift.

Here is my steering and lift pump.

What's the PTO pump used for??

 

[J_J]

Hyd Post hole digger

Hyd flail mower

Hyd stump grinder

Hyd 4ft trencher

Any hyd implement.

 

[SIMassey]

The fluid from my current pump goes to the steering first and then to the loader.

The steering has priority, and will stop the lift if steering hard. When finish steering, the fluid bypasses to the loader.

I should do some pressure testing in normal conditions and then under a load to see if the idea is even feasible.

I am not familiar with the Power Trac, but IMHO, I am suprised that they would tie the lift and steering into the same system

without having a larger capacity gpm. You stated the lift is inoperable when steering hard. I would view the lift as any other

attachment and run it off the PTO pump like any other attachment unless there is some reason you can not do that. Again, I am

not familiar with the Power Trac

 

[J_J]

You could do that but when using hyd implements, you would have to reconfigure the PTO circuit for PTO only.

The steering unit has priority over the lift, and there is a PB circuit so when not steering or lightly steering, the flow is passing downstream to the lift.

 

[Xfaxman]

What's the PTO pump used for??

I am not familiar with the Power Trac, --------------

PT 1445

 

[J_J]

The PTO circuit can be used with hyd motor attachments only. Will not hold a cyl in place.

My valve is a lever type, variable speed spool and most of the other PT's have a solenoid PTO valve with full on flow. .