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To sashiery, let me start off by saying that you have a very good looking tractor. For anyone reading this that may not be familiar with how the variable speed drive (aka. variator) system works on the 110, 112 and 200 series I would highly recommend that you read the appropriate section of the applicable Service Manual (SM) for your particular piece of equipment. It is a purely mechanical system that has several components that need to be functioning correctly but also properly adjusted for optimum results.

The commonality of the cases being sited is primary and/or secondary belt slippage under high load (i.e. torque) conditions. Even if the variable speed drive system is in optimum condition, under high load conditions something eventually has to give. Judging from your rear tire setup I certainly would not expect rear tire slip and the K-Series are known for their excellent lugging ability so the weakest link appears to be the drive belt system.

Although you did not mention it, I would assume that you are using the correct JD primary & secondary drive belts and not aftermarket. The JD belts will have the optimum V-belt geometry (including angle) to maximize the belt/sheave contact area. Both the transaxle and engine drive sheaves are fairly large diameter so I would anticipate that the belt slippage is likely occurring at the variator sheave. To maximize contact area try operating the tractor with the vartiator control lever in one of the center positions and not one of the extreme positions. Reason being, if operated at the extremes one side of the sheave will have a larger effective radius (with more sidewall belt contact) while the other side will have a smaller radius (with less belt sidewall contact). The belt on the smaller radius side will in turn be more likely to slip.

The other thing is perhaps you are being overly zealous on how much pretension you are placing on the variator spring. It has been my experience that when properly adjusted one will notice little change in ground speed when modest increases in drive train load are encountered but very noticeable changes in ground speed when significant increases in drive train load are encountered. As an example, with all my 200 series tractors I can drive up a fairly steep incline without much change in ground speed but if I try the same maneuver while pulling a loaded dump cart the tractors will slow to a crawl. I am thinking that by having your variator spring tightened too much you are decreasing your drive train’s ability to self adjust the variator position to counter increased load changes. Unfortunately, I do not find the 200 series Service Manual to be particularly helpful on what constitutes a good base setting for this adjustment. Perhaps someone else can enlighten us on that setting.

From SM-2105, additional items to check are listed below:

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