Gas hydraulic schematic

[JohnR]

Helping a friend building an SD40 engine. This is a project somebody started a few years back and never completed.
Looking for a general schematic for the hydraulic system (generic).
Each truck is driven by a gerotor motor with the power supply being a Kohler Magnum 8 HP motor with a 2 stage pump from Northern Hydraulics ( never run ).
If somebody could supply a simple schematic on the hydraulic it would be greatly appreciated.
Thank you.

[ERIE S-1 BERKSHIRES]

Are you looking for the old rail systems with the ball valve bleed off also known as the two stick control

[JohnR]

I am not familiar with rail systems setup. If possible could you direct me to where to go to look at this setup.
Thank you for the response.

[ERIE S-1 BERKSHIRES]

John what state are you from?, I am from Ohio, the local Club I hang around northeast Ohio live Steamers has 1 engine with this setup one rod is for forward neutral and reverse the other closes the bypass which starts the locomotive to move

[Steggy]

...with a 2 stage pump from Northern Hydraulics ( never run ).

You will probably not care for the way that pump will behave. The "gear ratio" between high flow, low pressure and low flow, high pressure is 1:4, and the transition from one state to the other occurs at around 600-800 PSI, which means you'll likely spend a lot more time in "low gear" than you'd like. Incidentally, when the transition does happen it will be fairly abrupt, causing the locomotive to lurch.

I'd recommend using a single stage gear pump, preferably one that is has a cast iron body. Not knowing the displacement of the traction motors, I can't make a recommendation as to pump displacement.

[JohnR]

Erie S I think the "kit" originated from the estate of one of your members. I am located at E.M.L.S. At Sandusky
BDS, we are going to use the pump it came with do to the fact the individual is on a tight budget.
As far as controls there is a 4 way 3 position valve for forward reverse.
As far as speed control any recommendations on flow control valve ?

[ERIE S-1 BERKSHIRES]

For flow control it's just a ball valve roughly 3/8 to 1/2 in, forged bronze body 600 working PSI, John do you know where Neols Club is located in Medina County, they have a meeting Second Sunday of the month if you can come I can meet you there

[Steggy]

For flow control it's just a ball valve roughly 3/8 to 1/2 in, forged bronze body 600 working PSI, John do you know where Neols Club is located in Medina County, they have a meeting Second Sunday of the month if you can come I can meet you there

600 PSI is much too low. Pressures in these systems routinely reach 1200-1500 under load. Any ball valve used should have a steel body. Take a look at this item, for example. Where possible, use SAE O-ring parts instead of pipe threads—the referenced valve is available either way.

[ERIE S-1 BERKSHIRES]

This system is high-volume low-pressure so it never reaches high pressure, Under full load I think it reaches 475 PSI before the wheels slip, rail systems use this for a long time I know of four engines this use the same setup haven't failed yet, and as for the two stage pump there is a pressure setting that will not allow it to kick down!

[rkcarguy]

...with a 2 stage pump from Northern Hydraulics ( never run ).

You will probably not care for the way that pump will behave. The "gear ratio" between high flow, low pressure and low flow, high pressure is 1:4, and the transition from one state to the other occurs at around 600-800 PSI, which means you'll likely spend a lot more time in "low gear" than you'd like. Incidentally, when the transition does happen it will be fairly abrupt, causing the locomotive to lurch.

I'd recommend using a single stage gear pump, preferably one that is has a cast iron body. Not knowing the displacement of the traction motors, I can't make a recommendation as to pump displacement.

+1. I wish these were available with a much higher pressure transition, such that if the hydraulic system was overloaded it would "downshift". These are designed for log splitters though, so the ram will quickly come up against the log and then transition to a slower more powerful ratio to split it. This isn't going to work well for propulsion unless it can be locked out of "low", which I have seen a few which are.

[rkcarguy]

This system is high-volume low-pressure so it never reaches high pressure, Under full load I think it reaches 475 PSI before the wheels slip, rail systems use this for a long time I know of four engines this use the same setup haven't failed yet, and as for the two stage pump there is a pressure setting that will not allow it to kick down!

Interesting, I'd like to see the system layout and see one in action.

[ERIE S-1 BERKSHIRES]

The original Rail Systems from Oregon used 11 gallon minute log splitter pump two stage without any problems! My buddy Harry boivin is working on a hydraulic schematic