Twin Piston Oil Pump Project

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Pipescs
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Joined: Wed Feb 03, 2010 10:16 pm
Location: Lester Alabama

Twin Piston Oil Pump Project

Post by Pipescs »

This is actually a sub project for the Rust Bucket. It is to be a Steam Oil Pump from scratch to fit a 2.5 inch engine.

I was not going to post this work, but thought some may find it interesting to comment on.
Test - Sheet1`a.jpg
It will not be scale, being heavily influenced by the one shown in Kozo Hiraoka's book "The Pennsylvania A3 Switcher" which is a 3/4 inch scale engine.

This project started as a simple blow up of his design but I received a lot of input that a twin pump would give a more consistent flow of oil to the two cylinders.

Primary changes are in the drive system as I wanted the pump strokes to be 180 out. This called for an overhead eccentric shaft.

A secondary goal in this effort is to complete it as a tutorial on Solid Works. So all my drawings shown here will be 2D prints that I used in the shop. The Process has been to draw it, cut it out and then go back and fix the drawings.
Test - Sheet1d.jpg
Test - Sheet1b.jpg
Test - Sheet1c.jpg
Last edited by Pipescs on Sat Jul 16, 2016 8:25 pm, edited 1 time in total.
Charlie Pipes
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Pipescs
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Re: Twin Piston Oil Pump Project

Post by Pipescs »

Actually the pump could be used for a 1.5 inch scale locomotive as the piston size is tailorable.

The first parts I tackled are the Pump Body Nuts. These nuts secure the pump body to the tank floor. They also provide the oil ports to allow the oil to pass into the pump.

These were made from 1/2" hex brass bar.
DSC_4285.jpg
DP Pump Nut - Sheet1.jpg
Charlie Pipes
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Pipescs
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Re: Twin Piston Oil Pump Project

Post by Pipescs »

I should mention here, although he may not want the world to know he is involved in this mess, that Pontiacguy is continuing to be my mentor on this and is helping machine the parts.

The main pump housing is an enlarged version of Kozo Hiraoka's design. It looks simple and I see no reason to change it. I simply enlarged it as he describes in his books. He gives guidance that the pump (for a 3/4" scale engine) should only be enlarged by a factor of 1.5 to run it in a 1.5 inch scale version of the A3.

As the Rust Bucket cylinders are around 2 inches in diameter, I believe that having one pump for each side will give me enough oil. If not I can increase the flow by going to a larger piston. Smaller if needed.
DP Pump Body - Sheet1b.jpg
Charlie Pipes
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Pipescs
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Re: Twin Piston Oil Pump Project

Post by Pipescs »

The Pump bodies were machined out of half inch hex brass bar.

To keep them concentric I used a 5C Collet for all the work.

First I drilled out the cylinder undersized and reamed it to .125"

Then all the outside work and threading for the Pump Nut.
DSC_4293.jpg
The four oil inlet holes in the Pump Body were done using the hex collet in a square fixture on the milling machine.
DSC_4296.jpg
Charlie Pipes
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10KPete
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Re: Twin Piston Oil Pump Project

Post by 10KPete »

I'm watching very closely, Charlie! Very timely, as I'm considering one for a compound marine engine. The externals
need something automatic.

Pete
Just tryin'
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Pipescs
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Re: Twin Piston Oil Pump Project

Post by Pipescs »

The tank dimensions that are shown Hiraoka's Book is for a one cylinder pump.

So I drew these really nice drawings of a 2x2x2 tank to be made out of 1/8 x 2 inch plate that I ordered from McMaster Carr.

For the early Prototypes I went with a little dirtier solution that is actually working out very well.

I cut a chunk out of a trailer tongue I am replacing. It is a very rusty 2x3 inch thin wall tubing with a 1/8" x 2" bottom that was MIG welded in place. My first MIG welding by the way.
DSC_4299.jpg
Attachments
DSC_4300.jpg
Charlie Pipes
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Pipescs
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Re: Twin Piston Oil Pump Project

Post by Pipescs »

As you can see my two prototype tanks are still showing a lot of rust inside. This after a lot of sanding.

After church today it will be time to swing by for a jug of CLR Rust Removal to soak them in for day or two.

The next step is to weld on the two mounting tabs for bolting them under the running boards. I may move the tabs to the inside lines of the tank.

My first tank has the pumps a quarter inch farther apart than they should be. I forgot to take into account the wall thickness. Pontiacguy is making me an eccentric that is a little wider to cover this. It is really not a critical measurement on this placement so the tanks could be much narrower.

Actually the only critical measurement is the height of the drive shaft above the oil ports. The pump ram has to raise just enough to clear the oil inlet holes and go down just enough to produce one drop of oil per revolution.
DSC_4308.jpg
DSC_4307.jpg
Charlie Pipes
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Pipescs
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Re: Twin Piston Oil Pump Project

Post by Pipescs »

The pump Plunger Head is machined from Silicon Bronze with the Plunger being Stainless Rod
DP Pump Plunger Head - Sheet1.jpg
DP Pump Plunger - Sheet1.jpg
This is really the only major change to Mr. Hiraoka's design. He used a simple crank assembly with a follower that was slotted. Having to drive two pumps it was easier to run the shaft across the tank completely and use a long eccentric.
Charlie Pipes
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Pipescs
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Re: Twin Piston Oil Pump Project

Post by Pipescs »

Today I am working on the Eccentric Followers. they are turned from 13/16th Bronze Rod then finished up in the milling machine to do the flats, slots and Plunger Holes



The Eccentric Shaft Drive Bushings are turned from half inch hex brass using a hex collet.
DP Drive Bushing 2 - Sheet1.jpg
Charlie Pipes
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Pipescs
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Re: Twin Piston Oil Pump Project

Post by Pipescs »

Bushing and Nut both machined from half in hex brass.
DP Drive Bushing Nut - Sheet1.jpg
Charlie Pipes
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Pipescs
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Re: Twin Piston Oil Pump Project

Post by Pipescs »

Quick note on my drawings and tolerances

The drawings are roughed in right now and will be getting cleaned up a lot as I figure out how to cut the parts.

Understanding the concept of implied tolerances based on how it is printed on the drawing, I will go back and reset the units to .000 vise the .0000 that my Solid Works is set to.

Actually, having worked on Aircraft all my life I am using the time tested TLAR Standard that is quite prevalent in my previous work. (TLAR standing for That Looks About Right)
Charlie Pipes
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FLSTEAM
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Re: Twin Piston Oil Pump Project

Post by FLSTEAM »

I use the TLAR and SWAG standards a lot...........

John B.
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