Author Topic: Caterpillar piston&liner mortar (Read 1246 times)

maddmaxx · « **on:** May 12, 2004, 07:44:08 AM »

OK Here I am with a lot of ignorance and questions. Have a mortar made from a liner from a 583 Caterpillar tractor. Nominal dia. 6". Made to withstand the explosions of diesel fuel, not bp. It works, but I don't trust it except in a post hole 3' deep. Liner won't take weld, so must be cast. Steel or iron? So put band around below flange and welded it to plate. Injector shield removed for fuze access. Depression in top of piston held 1/4 cup bp. Piston must be put in from bottom of liner after rings are compressed, then assy turned end for end with mud around fuse. Assy goes in post hole, fuze is lit, and after an interminable length of time piston exits post hole. Keeps going up for approx 5 seconds. Looks like thimble in the sky. Doesn't tumble in travel. Hole with 10 deg angle brings piston down within 100'. This is fun, but a lot of trouble.Don't have a CAT engine block to support liner. Would an old cut-off oxy cyl prevent the need for the post hole? Trunions would make trajectory adjustment much easier than post holes. Tell me something. Maybe I'm mad after all, but I need to know. Cat ain't out of the bag, yet. Neighbors think I know what I,m doing.So if I need straightened out, I'd rather hear it from you all.
Another mortar shoots apples w/ a small chg. Or makes applesauce!

Double D · « **Reply #1 on:** May 12, 2004, 10:58:14 AM »

First Step!

Go to your nearest Cat dealer and ask them what cylinder liners are made out of.

My guess, not a WAG not a SWAG but just a guess is that it is some sort of seamless steel.

When you find out let us all know and we will be able to guide you from the there.

Cat Whisperer · « **Reply #2 on:** May 12, 2004, 03:37:31 PM »

I never cease to be amazed at what people come up with that works.

It's hard to say what flavor of steel it is. DD steared you right. Good way of using it, by digging a hole. I'd often dreamed of using a carboard tube from a roll of carpet and a stick of dynomite to launch a paint can into orbit - good for ONE shot.

The piston should be relatively light and therefore not agressively high pressure, but if it's cast steel or iron it might be a bit brittle - assuming they went for abrasion resistance over tensile strength.

Going mostly up, your times of flight will be somewhat less than at a 45degree angle. (as will lighter bullets vs heavier bullets)

good luck and keep safe!

maddmaxx · « **Reply #3 on:** May 13, 2004, 05:03:47 AM »

For what it's worth, friend of mine said "pappa-san" was using PVC for a mortar tube. Kept it hid it in his chimney. He got found out when the back-blast blew all the thatch off his hut!

jj1 · « **Reply #4 on:** May 13, 2004, 01:17:12 PM »

the cylinder sleeves on most engines are cast.
usually it is chrome molly iron alloy. be carefull
they are brittle.

maddmaxx · « **Reply #5 on:** May 20, 2004, 03:05:45 AM »

Just got the word back from CAT. Engine cyls are cast iron. Tells me all I need to know. (Glad I shot it from a post hole) Maybe I could use it to make an air compressor for launching stuff. Too bad CAT didn't design their engine cyls with mortars in mind. ...oh well. Sure was impressive how well the rings held the compression, though. :shock: