Sachs Orbit hub on 1973 Jack Taylor
Wanting to continue my deep dive into internally geared hubs, and looking for a few good projects to stave off the winter doldrums, I decided to overhaul the Sachs Orbit hybrid hub on my 1973 Jack Taylor, as it has been feeling a little sluggish and probably needs some attention, given that I’ve done nothing to it since I acquired the bike years ago except to give it a drop of oil now and then. The previous owner of my Jack Taylor had modified the original rear wheel to include this hub, instead of a standard freewheel type hub, thus allowing the removal of the front derailleur and one chain ring.
In researching the history of the hub, I discovered that the Orbit was part of a component group (the “Commander”) that featured index shifting and was introduced in the early 1980’s by Sachs-Huret, the original company Fichtel and Sachs having purchased a controlling interest in Huret at about this time. This gave Sachs-Huret the jump on Shimano, who came out with their S.I.S. indexing system in 1984. It should be noted that SunTour introduced its unpopular version of index shifting in 1969, and of course, index shifting existed far earlier than that with the Schulz Funiculo derailleur patented back in the early 1930’s (these derailleurs could also handle 40T cogs!).
The above catalog scans of the Commander groupset feature the six speed version of the 2 speed hybrid hub, giving 12 gears overall. The Commander’s method of indexing used a clicking shifter paired with a cam on the derailleur parallelogram. It never caught on, perhaps because of the clunky looking shifters and the mysterious hub, as well as the use of a cam on the derailleur which meant a little more difficulty in tuning the derailleur properly. The whole thing may have been a bridge too far, and once Shimano came out with its easy to set up and use indexing, there was simply no way the Commander groupset could compete. And that may explain why these hubs are so rare. Over its relatively short lifespan the Orbit was offered in 5, 6 and 7 speed versions, and many of these hubs came with drum brakes.
What is a hybrid hub? It’s an internally geared hub (IGH) that also has room for more than one cog on its driver/freehub. This means that for bikes that cannot have a front derailleur (folding bikes come to mind), for bikes with small wheels that need taller gearing, or for cyclists that prefer not to have more than one chainring up front, adding a hybrid hub can provide the same gear range as a wide ratio triple crankset. Over the next few decades SRAM went on to offer a whole range of hybrid hubs, but currently I believe that only Sturmey Archer is in the hybrid hub business.
Early 1990’s NOS Sachs Orbit hub
Because of the difficulty in finding parts for these hubs, I purchased a NOS version a while back. This one was built in the early 1990’s. Before overhauling the hub on my Jack Taylor I thought it wise to use the NOS hub as my learning platform. In the process I noted some differences between the older and newer versions, which I will comment on below.
John Allen, on the Sheldon Brown site, has some good information on the Orbit hub as well as some links to other sites with helpful resources. In addition, disraeligears.co.uk has extensive commentary regarding the Commander groupset and useful catalog scans as well.
Sachs Orbit schematics
Catalogue scan courtesy of disraeligears.co.uk
With its relatively simple operation, as compared to a three speed hub, I hoped to be able to overhaul the Orbit even though there are no service manuals available. The above hub schematics are useful, but don’t take the place of a step by step service manual.
The first step for my NOS hub was to remove the cogs (this hub unfortunately has no outer hardware, but if it did, you would remove that first). The larger cogs are splined, and the smallest two cogs are threaded. Each cog is separated with a spacer. From there, it should be noted that the drive side cone is machined to the axle, so all work is done from the non-drive side. These hubs do not use anti-rotation washers, and should work with fine with any kind of rear drop out, vertical or horizontal because the hub uses a derailleur for chain tensioning. The axle’s M10x1 threading is not compatible with Sturmey Archer, nor with other Sachs/SRAM hubs.
Once the non-drive side cone is removed, you can lift the hub shell out of the hub body. The hub shell has ratchets on the inside to engage the pawls. The hub body now consists of the driver, the planet cage and the pawl cage, as well as the clutch spring and “clutch pin”, also called the “sliding selector block” on the schematics. There’s a circlip holding the clutch spring in place which is removed next, and the clutch spring comes out along with a stepped washer. Then, the pawl assembly comes off. You’ll note that the assembly has two sets of pawls, one set on the inside and one set on the outside. You can also see that there is an outer gear ring on the pawl assembly that engages with the inner gear ring on the driver.
When the pawl assembly is off, the “clutch pin” has probably fallen away. This is where the indicator spindle will connect so that the pawl assembly can be shifted. The planet cage comes out next, but not before removing another circlip and washer, which hold the planet cage in place. The washer is keyed and needs to be rotated to match the axle so that you can remove it. The planet cage has another gear ring on its head portion that connects to the inner pawls of the pawl assembly.
There’s another piece inside the driver that helps to orient the planetary gears. Once the parts are all out, the driver’s dust cap can be removed. Note that it is “right side up” on this hub. From here, I soaked all the parts in citrus degreaser, cleaned them with alcohol and then was ready to start re-assembly. Since this is a NOS hub, there wasn’t much scrubbing involved.
Clean and shiny parts ready to go.
Clutch pin installed with spindle attached
Pulling up on the spindle the gear ring disengages from the driver
The pawl assembly at rest
The reassembly process went okay, except for a few problem areas to note: you must reattach the spindle to the clutch pin after assembling the planet cage but before adding the pawl assembly. When shifted, the pawl assembly is moved to the left side of the hub, disengaging it from the driver’s gear ring. The inner pawls of the pawl carrier then engage with the planet cage’s smaller gear ring, thus giving a lower gear (about 25% lower). Another difficulty in the reassembly is that the clutch spring must be compressed and held down while also trying to push the circlip into place, something that can take more than a few tries to complete. And, don’t let your hands off the circlip, as it can go flying around if you fail to push it on to the axle, and since it is a small part it can be hard to locate.
Now it was time to overhaul the early 1980’s hub on the JT. The first thing I noticed was that the older hub has a sealed bearing mechanism which includes a dust cap on top, as part of the cone, and an “upside down” dustcap underneath, which creates a seal, on both sides of the hub axle.
Whereas the newer hub has one regular dustcap on the drive side, and one upside down dustcap on the non-drive side. No seal is created with this method.
Upon disassembly I found the JT hub to be pretty dirty, with a lot of black greasy oil accumulated around the planetary gears. Also, there was an extra part on the planetary gear assembly that sits at the base that wasn’t part of the newer hub. Its purpose may be to reduce drag, but I’m not sure about that. Everything cleaned up fairly easily except for the tiny grooves in the gear rings, which needed extra cleaning with a brash brush and pipe cleaners. The quality of the machining and the metals used seemed identical between the two hubs, and both appear to be well built and solid.
I was unable to remove the cogs on the older hub, but that fortunately did not interfere with the overhaul process as it’s easy to just leave the cogs on the drive. It was a little more difficult to get the cogs clean, however.
Lubrication is important in these potentially inefficient hubs. While reassembling the NOS hub, I simply applied Phil’s waterproof grease to all the parts, plus some Tenacious Oil on the pawls, to protect it from shop wear. But for the hub I am using I needed to gather together the MANY lubricants needed for these types of hubs: marine grease for the troughs of the upside down dustcaps (to make a waterproof seal), Phil’s waterproof grease for all the bearing assemblies (less viscous than the marine grease), Sturmey Archer lithium grade “00” grease for the gear rings and planetary gears, and Phil’s Tenacious oil for the pawl springs and pawl bodies, then 10-30 automotive oil on all the rest of the internals. After much reading on this subject, this combination seems best for weather protection and drag reduction. Guidance on internal hub lubrication can be found at the Sheldon Brown site, the bikesmithdesign site, and at the Aaron’s Bike Repair Site.
The hub is now back together and ready to be taken for a test ride. Hopefully it will feel more lively after being cleaned and with fresh lubrication. I’ll have to save that for another day – it’s snowing outside! Meanwhile, I plan to tackle the overhaul of a few more IGH hubs over the winter.
