We seeded with Wheatland Plows for years. They were in a gang of three. Wish I had a picture of them hooked up. 
Wheatlands were very popular around here at one time 
A grain farmer has these as yard art 
 

ray we call em disc plows. what you blokes call disc harrows we call offsets because the gangs of discs are offset to each other and you get 2 types adjustable or fixed and the adjustment is either manual or hydraulic.
in general they sized by the number of discs referred to as plates. so a 21 plate has 21 discs.
dad worked for bonel bros as a factory hand assembling and repairing the range of implements they manufactured.

Ray54, I think that each blade on a separate bearing/axle would be correct.
I know my Dad spoke of pulling disc plow in vetch cover crop, not nearly as prone to plugging up as a moldboard even with rolling colters.
That was with RD-4.
Thanks for the clarifications and help.
CTS

Neat pictures of what us flatlanders here referred to as a "oneway". Never saw one with a seed box on it around the plains states so thanks Gary for posting that.
Our ground was often hard and baked so the oneway had a weight box on it to help keep the oneway trailing straight. They were ideal for filling ditches or revamping terraces.
Still have a couple out in the old junk pile.

had them up here too...far as i know called one-ways....but basically a heavy disc with a seed box...and most of them lost the seed box after awhile...
-in our heavy clay based soil that was still handy....a heavy disc is great for cutting up old sod and whatever..me thinks best farm implement ever... next to plow

 
July 1941
Colfax, Washington
Tractor and combine repair shop.

 
1939 Feb.
8 a.m. Migratory field workers pulling carrots in a field. Note carrot digging tractor in background. "They'll sleep in the row (to hold a place in the field) to earn sixty cents a day." Near Meloland, Imperial County, California.

seyser wrote:

 

July 1941
Colfax, Washington
Tractor and combine repair shop.
"Now that there's a rod mister! that's what I'm talkin bout!"
 

Oneways. There were a lot of those used in Western Kansas. Oklahoma panhandle, and West Texas back in the day.

In fact they were the cause of the dust bowl. Left the ground level with a lot of fine dirt and dry weather. Then Mother nature started

blowing her breath and well you get the picture ....DUST.

Then a company in Hooker, Oklahoma started building Home (pronounced hayme) chisel/sweep plows and that helped keep the

dust from blowing a little.

I have only seen 1 oneway with seed feeder tubes on it. The seed box was missing .

I have a oneway and used it last fall to cut the russian thistle out of my field and then used a land plane to cover up my mistakes

made with the oneway before planting wheat. I was lucky it rained a little and then planted before the big blow.

Claney

Oneways. There were a lot of those used in Western Kansas. Oklahoma panhandle, and West Texas back in the day.

In fact they were the cause of the dust bowl. Left the ground level with a lot of fine dirt and dry weather. Then Mother nature started

blowing her breath and well you get the picture ....DUST.

Then a company in Hooker, Oklahoma started building Home (pronounced hayme) chisel/sweep plows and that helped keep the

dust from blowing a little.

I have only seen 1 oneway with seed feeder tubes on it. The seed box was missing .

I have a oneway and used it last fall to cut the russian thistle out of my field and then used a land plane to cover up my mistakes

made with the oneway before planting wheat. I was lucky it rained a little and then planted before the big blow.

Claney