John Deere 803M–959M: travel, boom and leveling packages

Choose the M-series carrier and travel system before the head

Deere's 800M brochure separates the 803M, 853M and leveling 859M undercarriages. The 803M uses the U6 Extreme Duty arrangement; the 853M moves to U7, and the 859M uses the longer U7L. The published lower-roller counts also change.

A harvesting head mounted to the boom does not identify the carrier beneath it, so inspect the track frame and leveling structure independently.

Standard Travel and Dedicated Travel are separate hydraulic configurations in the 853M/859M schedule. Dedicated Travel adds its own travel pump arrangement, and the higher-output engine choice is associated with that package. The ordinary main-pump rating alone cannot establish how well the installed machine combines tracking with boom and saw work.

Demonstrate those functions together with the fitted head.

The brochure distinguishes Smooth Boom Control from optional Intelligent Boom Control on harvesters. SBC moderates machine movement; IBC coordinates the boom joints from the head's commanded position. Rapid Cycle System has another purpose: it coordinates the felling-head arm cycle, can be switched off, and stores operator preferences.

Those names describe different controls. Ask which system is present and try its actual operation.

Reach also depends on the front. The extended-stick option in this edition belongs to the MH harvesters, with plumbing and attachment restrictions of its own. It is not a general reach upgrade for every M feller buncher.

Deere's lift tables use bare-pin loads, while the head schedule separately includes adapter and wrist mass. Subtracting the installed attachment matters before treating a bare-pin figure as available tree load.

The larger 900M machines have their own equipment boundaries

The original 2018 900M publication describes dual swing drives and distinguishes feller-buncher fronts from MH harvester fronts. Its optional through-nose hose routing is a harvester feature. The slope-monitoring option is specifically listed for the 959M and 959MH; a leveling chassis alone does not prove that monitor was ordered.

Inspect the cooling enclosure, too. The 800M publication groups external screening, a sealed cooler compartment and a variable-speed reversing fan as a debris-management system. The 900M brochure describes both timed reversal and an operator-commanded cleaning cycle.

A fan that rotates normally has not demonstrated the reverse function, and a clean outside screen does not show the condition of the enclosed cores.