Kubota GB13 – GB20 hydraulics, PTO and implements: what can you do with it?

The hydraulics and PTO shaft make the Kubota GB13, GB14, GB15, GB16, GB18 and GB20 true workhorses. In this article: how the lift with position control works, the PTO speeds and the notorious reverse position, and what implements you can realistically run with 13 to 20 hp.

Suitable for the entire series: Kubota GB13 (D9/DA5/N), GB14 (B9), GB15 (B9/S), GB16 (K/FK/H), GB18 (K/FK) and GB20 (K/FK).

Kubota GB lift system: position control and lowering behavior

The lift works with position control: the position of the control lever corresponds to a fixed height of the lift arms. On the GB13–GB15, a 2-point linkage is standard (3-point JIS 0 was optional); the GB16–GB20 come standard with a 3-point lift according to the JIS 0 standard. Good to know: the lift has no downward pressure — it only lowers under the weight of the implement. Without an implement, it therefore hardly lowers at all, and that's normal. You control the lowering speed with the throttle valve; fully closed, the lift is hydraulically locked (handy for transport).

If the lift with an implement attached slowly sinks or moves jerkily, in practice contaminated or old oil is by far the most common cause — the system shares its oil with the transmission. Change the oil (see the capacity table), replace the hydraulic filter and clean the suction strainer before touching the pump or the control valve. Machines with the Monroe version also have a hydraulic tilt cylinder on the right lift rod; its hose is scheduled to be replaced every two years according to the maintenance schedule.

Kubota GB PTO shaft: speeds and the reverse position

Watch out for that reverse position: the last position of the PTO lever turns the PTO shaft backward. That setting is intended for Japanese tillers with a reverse function — never engage it with an implement that isn't designed for it. If you're wondering why your tiller is turning "the wrong way," the lever is almost certainly in this position. Always connect implements with the engine switched off, and use the PTO shaft cap when nothing is connected.

What can you do with 13 – 20 hp? Implements per model

PTO power and drawbar pull are two different things. At the PTO, the GB series delivers roughly 85% of engine power; at the drawbar, weight and tires are the deciding factors. In practical terms, that means:

These widths are practical guidelines for average conditions; on heavy clay or in long grass, choose one size smaller. At the time, Kubota supplied original accessories including a 14 kg front weight, wheel weights of 2 × 21 kg, and even a PTO-driven water pump (55 L/min). With significantly protruding or heavy implements, front ballast isn't a luxury: keep the front wheels on the ground, especially downhill.

Front axle and bi-speed turn

All GB models are 4WD; versions with bi-speed turn make the front wheels rotate faster in a sharp turn for a smaller turning radius at the end of the field. Only use bi-speed with four-wheel drive engaged and never on paved roads. Leakage at the front axle knuckles (dripping oil on the front rims) indicates worn kingpin seals — for the GB13–GB15, the front axle seal (SKU-96036, €27.50) is available, and for the GB16–GB20 the stub axle/rear axle seal (SKU-96068, €16.00).