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Hi, There are two variations of rockshaft units on the 420/430 series. One is the standard single piston unit, which has one lever and can only lift the 3-pt. The other is a two piston unit. It has one piston that works the main rockshaft and lifts the 3-pt and is controlled by one of the levers (the one closest to you as I recall). The other piston operates a secondary rockshaft with a single lift arm that is on the left side of the machine. That has an eye mounting point on it to couple to a set of mid mounted cultivators. The second piston is independantly controlled via the second control lever. There is a valve under the seat that allows you to choose dual independant control via the two levers, or use one control to operate both pistons at the same time. There is also a set of holes in the two lift arms on the left side that allow you to pin the two rockshafts together. In this configuration, the one lever sends oil to both pistons and the lifting power of both are passed to the 3-pt via the pin in the lift arms. Most machines have the two cylinders slaved these days to increase the lift capacity of the 3-pt. Not too many 420's are still operating cultivators, I guess. Anyway, when the system is slaved like this, the second lever is just left in the full raise position and usually locked in place by a bolt and wingnut. This system first appeared on the MT, while the standard M had the single unit. It carried on through the 40, 420 and 430 series (and may have lived on in the 1010, but I'm unsure about that). Generally, the Standard and Utility models had the single piston units, and the Tricycle and roW crop utility mldels had the dual piston units. Although one could order any model equipped any way that was desired. The T and W models generally worked row crops where a culitvator was a handy thing to be able to use on its' own, so I suppose that's why Deere configured things this way. The dual units must have cost quite a bit more than the singles, so I guess it all makes sense. Stan
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