sunstrand pumps and motors

[allprohydr]

I am looking for the model codes for all series of sunstrand pumps and motors. If I go on sunstrand website it only list codes for the 90 series. Any idea of where I can get the others from or if someone can send them to me? What can anyone tell me about a 20-20225 89-26-52145 CCW 21 spline

[Doug Hanson]

[allprohydr]

Thanks for the reply. Can you scan any model code info you have and email or my fax is 252-746-3173. I run into alot of sunstrands and I can't determine what they are because the only model code info I have is for a 90 series. Thanks

[Doug Hanson]

18 degree size 20 pump is 2.03 cui/rev
Sorry, the model code book I have is 140 pages, so I won't be scanning that too soon. No time these days, or I would already have an electronic version. The good news is there is no copyright on it, so reproduction is not a problem. In the mean time, feel free to posts requests as you come across them. Model codes are rarely needed, unless your trying to identify details without taking the unit apart.

[allprohydr]

Can you tell me if the valve plate and cylinder block on most pumps are they completely flat or is their any angle. I know most look flat but someone said they were a slight angle and if so what angle is it. On the ones like RexRoth they are very concave and what is that degree. Also do they make a machine to relapp the surfaces for either type and if so what is it called and where might I find one used?

[Doug Hanson]

Pumps with flat barrells and valve plates like sundstrand 20 series and 90 series have faces that are dead flat. Well ,3 to 4 light bands under an optical flat and monochromatic light. That works out to 12 millionths of an inch or flatter.
The concave barrells of rexroth bent axis units have a radius. I don't know off hand what the radius is. I was going to build a machine for re-grinding and lapping the concave barrel and convex lens plates, but I havn't gotten around to it and probably will never get the chance.
The flat barrells and lens plates are a lot easier. Lapping tables are pretty common, Lapmaster and Spitfire are the two most common I believe. My unit is a lapmaster and has a 36" table with three rings on it.
Concave barrell faces can be hand lapped in a lathe or polisher. Put the barrell in the chuck, apply a bit of very fine lapping compound, hold the lans plate centered to the barrel (a guide pin makes this a little easier). Watch the fingers though!

[allprohydr]

Thanks,
I have looked at a few on line. Does a monochromatic light have anything to do with checking the accuracy of it when it is complete or nothing at all. You said yours was 36. For doing valve plates up to about 6 or 7 inches what is a good size to get. Also if you lap a valve plate (the grooves in it normally depending on rotation) how much can you get by with without have to have those recut and what are those cuts really for?

[Doug Hanson]

Usually people use the optical flat and light to check how flat the table is with a dummy piece and don't usually check each piece. It takes longer, but I prefer checking every piece I lap. After the piece is lapped, it must be polished with super fine polishing paper on a flat holder, or piece of glass, other wise the dull surface won't allow the lines to show up through the lens. If a piece is too far out, no lines will show up. If a piece is absolultely dead flat, almost never, it will show up as a bulls eye.
I think the rings on my 36" table have an id of 15". Way larger than needed for doing valve plates, however I often lap the face of the port end cover on a pump, as this also is a sealing face to the backside of the valve plate. Although it is not a rotating seal, it still needs to to be flat. I also lap mechacnical seals out of final drives, which are usually 10 to 13 inches in diameter.
There are specs for how much can be lapped off of valve plates, wear plates, bearing plates, barrell face, piston shoes and an overall stack height that must be maintained. Valve plates should never be lapped to the point of removing the lead in grooves which feather the eposure of the (lower) pressure in the pumping cylinder to the existing high pressure at the outlet port..

[allprohydr]

I'm looking for a sunstrand pump and motor good casing that I can rebuild for a test bench do you have any idea of who may have a reasonable one or do you. Also do you have a test bench to test your pumps, if so what kind. I am looking at building my own although the more people I talk to it seems to be a challenge unless I can get hold of the right information from the right person. Thanks for the info on the lap machine I'm still looking although new ones are expensive and with the economy it will take a while to pay for itself.

[Doug Hanson]

The person you want to talk to about lapping tables is Mitch Saunders at Saunders Machinery Company. Lapping tables are his specialty, buys and sells then. I don't want to post his email on a public forum, so if you shoot me an email (my adress can be found on the 'Contact' page of Hanson Hydraulics Ltd. home page: http://hansonhydraulics.com ) I will reply with his email adress.
I have a few 22 series variable pumps (manual controllers) and 22 series fixed motors. I also have a 27 series fixed displacement motor. I'm in the process of building a second 'regen style' test bench, but it is a filler job and nowhere near completion. For information on regen style test benches, check out Machinery Service and Design http://www.ms-d.com/
Basically you have a variable pump driven by either an engine or electric motor, which then drives your drive motor on the test bench (this can be fixed or variable, your choice) which in turns drives the pump your testing. Instead of the output flow from the pump you are testing going to a relief valve and wasting energy, it drives a regen motor (with rectifier block) which drives the regen pump, also variable displacement, this output flow feeds back into the initial drive loop. The only power you need to supply for this regen style bench is to make up for the inefficiencies of each of the pumps and motors on the bench. Usually with a 50hp electric motor on a regen bench you can test a pump up to 150 HP.
When testing a motor, there are a couple of ways you can do it, the way I like if your building a single station test bench is to use a six way selector valve or quick connects so that you can directly drive the motor being tested from the pump attached to your prime mover. The motor being tested now spins the test benches drive motor as a pump (charge pressure supply required). The oil from this motor/pump then feeds your regen motor and the rest is as above.