Piston Ballast Systems

now open up the third hole in both plates to 10mm to take motor sholder.

now tap the bearings into the first hole on both plates with the shoulders faceing inward(towards gears).

next take the main gear and shaft,cut a piece off tube to fit over the shaft,about an inch longer than the shaft.

next place the shaft and gear inside the tube,put in a vise and push the gear of the shaft as shown.

shaft and gear seperated,shaft is not used.

next find a 4mm brass nut and a small file.

This is the tricky bit,taking your time and insuring that you keep the nut central carefully file the round hole in the gear to a hex that will allow the brass nut to fit tightly in it,its not as difficult as it sounds the trick is to take your time,if you over do it a bit yu can gentley tap the edges of the nut with a hammer to expand it then push the nut into the gear in the vice.

now lossly asemble the gearbox as shown place the piston shaft through the gearbox and insure that the gear train runs freely.

take the gearbox apart again and locate the motor plate(aly one)place over the motor hole put the drill shank into the motor plate and gearbox case locate motor screw holes (long slots)with a 2.5 mm drill transfer motor holes to the gearbox as shown,then transfer to the second gearbox plate.

counter sink the motor screw holes on the inside faces.

screw motor to the gearbox plate with the original screws to check fit,as shown.

losly re asemble gearbox to check for free runing,if needed it is posible to slot out the motor holes to allow adjustment of the mesh between the motorgear and the idler.

another veiw of the gearbox losley assembled

again take the gearbox apart find some 4mm washers to use as shims on the piston shaft.

next it you need to fit the shims on the piston rod gear,the other gears should not require any shims, as the original spacers are re used,it will take several atempts to get the shims correct,put the gearbox together with one shim either side of the gear clamp the gearbox together in the midle so that the idler gear is tight to turn,look at the piston gear it will most likely need more shims,take a guess at how many and which side of the gear and install them,again clamp the gearbox try to turn the piston gear if its to tight take a shim out if there is to much end float put one in,make sure that the faces of the gears are not rubbing together if they are move one shim to the other side of the gear.

another view of shimming the gearbox.

Nigel,
What can I say, but WOW and Thank You! You have explained things so clearly!!! I can't wait to tear into this!

Just for the record, I have given up on the twin 60ml syringe arrangement, I think I discussed earlier.

Just too "wonky" (they twist etc.) and too much friction.

I am going back to a single aluminium tube etc., inspired by our German colleagues.

David

Do not overlook copper pipe. Some of the mechanical contractors may be in a generous mood if you tell them you are building a ballast tank for a submarine. They do not like competition. The nice thing about copper is that you can solder it together.

what size aluminum tube do you need david as i might be able to help could even weld an end plate on it for you if needed

https://2img.net/h/i1079.photobucket.com/albums/w507/david_forrest1/IMG_1951.jpg

https://2img.net/h/i1079.photobucket.com/albums/w507/david_forrest1/IMG_1950.jpg

Hope you will be able to see these. (I have had to post on Photobucket because I cannot host images on the Forum.)

They show my larger piston tank and control board as seen at Alfold. The smaller one for Resurgam will be very similar design but 40mm aluminium pipe. (I got a 300mm length for about £6 on ebay but thanks for your suggestions.)

I will use a standard nitrile O ring lubricated with silicone oil retained by a pipe cleaner! (Thanks for the tip Hein!)

These piston tanks have yet to be used in a sub and form my "long term development project!"

David

£6-00 for a 300mm bit of aluminium are you having a laugh david we put bigger bits in the bin have a word with Rich he'll tell you what i can get my hands on