Kubota KX91-3 and U35: track choices, auxiliary control and specifications

KX91-3 and U35: rear clearance versus track width

The U35's shorter rear does not mean a narrower machine. Kubota's minor-change workshop book gives the KX91 a 1310 mm tail radius and 1550 mm overall width, against 850 mm and 1700 mm for the U35. A passage between obstacles and a working position beside a wall therefore favour different measurements.

Establish which restriction controls the job before choosing between them. The rear swing measurement describes the rotating upper body; it does not establish room for the bucket, boom swing or an attached tool.

Weights also need matching equipment. The workshop comparison separates rubber from steel tracks and canopy from cab. Its KX91 canopy figure on rubber tracks is 7110 lb; the U35's 8234 lb entry is for a canopy machine on steel tracks.

Those two numbers do not isolate the difference between the basic chassis. A proposed trailer load needs the fitted enclosure, tracks and attachment recorded, rather than the lightest number associated with either name.

The thumb can need calibration after an electrical repair

The later finger-control service-port system stores the knob's left endpoint, neutral and right endpoint in the meter controller. Kubota calls for setup after replacement of the knob, meter or proportional valve. A thumb that creeps with the knob centred may have an incorrect initial setting or a sticking valve; replacing the hydraulic pump is not the first conclusion supported by this symptom.

The workshop troubleshooting chart separately considers a disconnected harness, loss of proportional-valve pressure and a main service-port spool that sticks.

Knob calibration, valve start-point adjustment and operator feel adjustment serve different purposes. The first establishes the command signal. The second compensates for when the attached hydraulic circuit actually begins moving.

The last changes the response around that starting point. A new actuator can require more than one of these adjustments. Kubota's chart assumes normal oil condition, sound pumps and otherwise working machine functions; its diagnosis does not cover a machine whose travel and digging functions are also weak.

Secure the attachment and use the serial-matched service procedure for powered tests.

Reservoir size is not attachment delivery

The minor-change specifications identify separate variable-displacement and gear-pump deliveries. The auxiliary outlet's rating is distinct from their combined flows. The same distinction applies to oil quantity: the hydraulic reservoir holds less than the complete installed circuit.

Before ordering a breaker or topping up after repairs, match the attachment requirement to the service-port specification and the refill operation to the relevant tank or system entry. Earlier catalogue figures remain in the comparison history so their different labels can be checked.

Kubota minor-change workshop manual, 97899-61260: I-7–8 and II-22–56