Jump to content

Unofficial Home of Old Simplicity & Allis-Chalmers Garden Tractors

Sign in to follow this  

RBT/ Planetary sickle mower info

Recommended Posts


Sickle mowers are a popular topic here and especially for those who acquire one of the more common FDT mowers and want to attach it to a newer machine equipped with a cone clutch. I thought I would chronicle some of the differences for those who are interested. Here is a list of the RBT sickle mowers by MFR#.990687: Introduced around 1971, was offered for the 3300 Series (non-cone clutch equipped) and did not have a planetary. They did use a different cable pulley bracket compared to the FDT sickles but the bar remained nearly the same. These mowers had the black paint on the belt gaurd and retained orange paint on the bar and knifegaurds.990785: Introduced in 1972 for use with 3400 Series tractors (cone clutch equipped). These bars utilized the same knife and cutterbar as the previous mowers but used a planetary drive mechanism to reduce the speed due to the larger drive pulley on the cone clutch.Here is a pic of the older style bar configuration:


1690030: Introduced with the System 7000 Series in 1975. These units featured a new bar with no removable rock gaurds. It now utilized serrated ledger plates (basically a knive turned upside down / see #26) instead of using "wear plates" as the earlier mowers did. There is one ledger for every knive. The bar is notched to match the knife shape. Here is a pic from the manual:


This one recenlty followed me home. It is a 1690030. I had read several times that the knives were believed to be a more standard agricultural knife and that the bars were actually made by Haban and attached to a Simplicity drive mechanism. I measured the knives and they are the same size as the Simplicity knives. They are 2" in width, 2.75" in height, and the hole spacing is the same at about 1-7/8."



The skids are made differently compared to the earlier mowers.


The hold-down clips are also different.


I have looked at pics of Habans mounted on Cub Cadets, JD's, and 300 and 400 Series ACs and they use a different bar and do have removable gaurds. I also believe the Haban knives are 3." The Haban skids do look similar though, as well as the hex-shaped pittman arm. If I have missed anything please add to the topic. Thank You.







Share this post

Link to post
Share on other sites

Also read in the Operator's Manual, that the planetary mower is to be run at 3/4 to full engine throttle as opposed to the early bars which run at 1/4 to 1/3 throttle. The planetary types are also more forgiving of running for longer periods of time at an angle.

Share this post

Link to post
Share on other sites

Never seen one of those before. The 300/400 series Allis's and AC built Homelites were the only ones I knew used that type of bar, but with a pipe type hitch on them. That hitch you have pictured looks to be more or less something all its own that I have seen.

The latest production planetary mower I ever had was from around the late 70's to early 80's, and I think the manual that came with it was copyrighted 1980. It was basically the same setup as the late ftd ones with the regular rock guards but using a planetary drive.

Share this post

Link to post
Share on other sites

Thanks for the pix and info. Definitely not a Haban made bar (I have several Habans to compare with). My planetary sickle bar mower has the same bar that the FDT sickle bar mowers use. The section assembly may be the same but not the bar assembly, the section pn's are the same. New bar assembly likely cheaper to manufacture/assemble and definitely lighter weight than the older style bar, stone guards, and ledgers assembly.

Share this post

Link to post
Share on other sites

Nice work. The later ones are harder to find and everyone finds an early one that they want on a later tractor. I picked up an FDT bar that was hanging on a 700 series. The guy that owned it complained that the belt only lasted a few minutes before shredding. He had just bought the whole set up from someone else that claimed it was "sold by the dealer that way in the 1970's and it worked fine". I explained they didn't belong together and made him an offer on the bar. He didn't believe me. About a week later, he stopped by and we made a deal for a partial trade with a 42" mower deck I had that needed lots of work, but would do for his "brush hogging". Tim

Share this post

Link to post
Share on other sites

I'm going to have to get better pictures of mine, but yours looks somehow different to me. #26 on the IPL is listed as "Plate, Lodger-Smooth" [it's typed as Lodger, most likely a typo?] and indicates 24 of them are on the bar. Unless I'm missing something it looks like your bar is only part #6 and those are missing. But when I look at pictures of mine those plates appear to be attached to the top of #6 and provide the fixed portion of the cutting action. Maybe your bars are aligned in the pictures and what I'm seeing as the bottom of #21 is really the bottom of #26?Either way, this is only the second 1690030 that I've seen and I really hope there are more out there! Every time I use mine I feel bad to be putting any wear on it. When I was on the hunt for mine I found next to nothing for information so I made a few youtube clips and put them up;

so people could see it in action.One seemingly knowledgeable gentleman at a tractor show told me that Haban made the bars after Simplicity stopped making the skinny bars as the sickle bar was going away and they didn't want to re-tool for the newer style teeth. The statement seemed reasonable to me at the time, but I don't know more about it than what I am told or read here.Is there an attachment registry here? I would love to know how many of the rare implements are out among the membership.







Share this post

Link to post
Share on other sites

Thanks for posting the pictures Brian. Yours looks to be in very good condtion. Mine does have the ledger plates. Its hard to see in the pics because the sickle sections are nearly aligned with the ledgers. Its almost like having two sets of knives except one set (the ledgers) are stationary and are attached to the bar/beam. Yes "lodger" is a typo in the manual.

Share this post

Link to post
Share on other sites
Sign in to follow this  

  • Who's Online (See full list)

    • Talntedmrgreen
    • MasterOfNone
    • DougAcord
    • BLT
    • TTDE419
    • Bear
    • CarlH
  • Today's Birthdays

    1. Carchief
      (57 years old)
    2. Geoff
      (56 years old)
    3. mohrds
      (51 years old)
  • Recent Status Updates

    • SonOfCreepfeed


      Thinkin' about this old girl.

      · 2 replies
    • Dean McFadden

      Dean McFadden

      Good morning peeps! I’m always searching for helpful information with my AC collection. Hope to find out new information and pass on my own experience in restoration. Here are some pics of my babies. I’m still looking for front rims for the 410 so yesterday I put the 310 wheels on took it for a drive. Working pretty good but still needs some carb work. Gotta get the 310 running next. Have a great day!😁

      · 1 reply
  • Adverts