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SERVICE SECTION (under construction...)

I'll use this section to give some simple instructions and background on some of the commoner maintenance and repair jobs you'll encounter when owning one of these great little machines. Click on each section title to go to the respective service/maintenance area. There's a lot more photos and information on my Facebook Page too.

Changing Brake Bands in Planetary 'Differential' Steering Units

For all Cletrac, Oliver-Cletrac and Oliver HG's, plus all OC3's, all early OC-4's and as an option on later OC-4's and on all OC-6's, controlled dfferential or 'planetary' steering was the name of the game. Lined steel brake bands, wrapped around brake drums in a dual differential assembly, and cinched at a cam, are tightened by simply pulling on the steering levers. The truly revolutionary aspect of this form of steering is that power is still fully available to both tracks during turns, unlike in clutched systems. This made Cletracs pretty unique for a long time.


Since there are arguments all over the web on this subject, here's how they differ in layman's terms:

The 'differential' in is not like the type you find in a car. It is actually two epicyclic units and two steering brakes. When a brake is applied, the drum is retarded and causes a compound train of planetary gears to reduce the speed of one track sprocket, whilst proportionately increasing the speed of the other. At no time does the inner track stop, consequently power is always available at each sprocket during a turn.


The chief advantage of differential steering is that both tracks remain under constant drive. It is impossible to direct the total power of the tractor to one track only, therefore the track and its mechanism operates more smoothly, and is not subject to sudden shock loads. A disadvantage of this type of steering is that the tractors minimum turning radius is fixed, consequently the manoeuvrability of the machine is less than that with clutch and brake steering.


The main advantage of clutch and brake steering is that it enables the tractor to be turned in its own length, hence Oliver's use of 'Spot-Turn']. Consequently, a tractor thus equipped possesses the maximum degree of manoevrability. The chief disadvantage of this form of steering is that it lends itself to abuse by allowing the total power of the tractor to be applied suddenly to one track. In addition to putting heavy shock loads on the transmission, this also produces heavy stresses on the tracks and track mechanism.


Replacing Worn Brake/Steering Linings

Steering and braking Cletrac and Oliver crawlers should be easy! A child could steer them, although allowing that is not recommended! If you are having to pull hard on either or both levers to steer, either your brake rod adjustment is way out or your linings are worn out*. The latter can lead to significant brake drum wear and scoring if the brass rivets are exposed in the linings.

Relining the steel bands is much easier than many imagine. In this photographic guide, we show step-by-step how to do it using supplied pre-cut linings and brass rivets. Arguably the only specialist tool required is a means of riveting. Other than that, a few simple clamps, a drill and two drill bits could suffice.

* 'Spot-Turn' or clutch-steering models may have other issues (not discussed herein).

Notes of Caution:

  • Cletrac to Oliver HG steel brake/steering bands came in two different gauges, which in turn took linings of different thickness. Either pairing will work in your machine (thin+thin or thick+thick), but you should not mix and match them.

  • Planetary and clutch-steering Oliver OC-4 linings are slightly different lengths.

  • The brake strut roll pins on later-style Oliver OC-4/OC-46 bands presents a bit of a challenge, but there's a reasonably easy remedy.

Let us know all relevant information when ordering.

Relining Kits Cost:

  • HG, OC-3 and early OC-4 bands (two loops at each end) — $25 each, including rivets.

  • Later-style OC-4 and OC-46 bands (two loops + two hooks) — $30 each, including rivets and roll pins.

Alternatively, you are welcome to send your brake/steering bands and we'll return them refurbished for $40/band (+ $13.60 Priority shipping + materials, as above).
So that's $153.60 all-in for most OC-4's & OC-46's. $143.60 all-in for HG's, OC-3's & early OC-4's.

                                                                                                                                  Prices subject to change without notice



Using Heli-Coils on Final Drive Gears

Heli-Coil inserts are diamond-shaped precision screw thread wire coils. When installed into Heli-Coil tapped holes, they provide a permanent, conventional internal screw thread that accommodate any standard bolt or stud. Heli-Coil inserts are larger in diameter before installation than the tapped hole. During installation the inserting tool applies torque to the tang reducing the diameter of the leading coil permitting it to enter the tapped thread. After installation, each high tensile stainless steel coil of the insert expands, thereby permanently anchoring the insert. In most cases, the Heli-Coil is stronger than the original bolt/stud to thread union.

Cletrac and Oliver Crawler final drive gear studs and hubs can be subject to enormous shock-loads, and more so as the machines evolved to become more industrial over time. The problem is compounded in clutched, 'Spot-Turn' units because twice the power is applied to one side, as the other side is disengaged! This is not the case in differential steering units where the applied power is equal at all times.

This section briefly shows how a good machinist can help you with re-tapping worn or broken hub stud pockets. It's absolutely possible to do this job yourself with very little expertise. For the expansive manufacturer's guide on Heli-Coils, click here to download a pdf or visit the Heli-Coil website [I am not an employee and nor do I derive any gain from recommending this product]



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Under development...



Under development...

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