Review: Kubota M7-171 Premium KVT tractor

New Zealand reviewer Brent Lilley climbs on board the CVT-equipped 170hp Kubota M7-171 Premium KVT tractor – a new contender in this horsepower range

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WHILE the Kubota brand has earned a solid long-standing reputation in the smaller horsepower tractor market, it now has its sights on a full line-up across the entire horsepower range. The first step in this direction is three new Kubota models, from 130hp to 170hp.

From the outset, the Kubota M7-171 Premium KVT offers a point of difference from other tractors of this size. The company has managed to squeeze an impressive 175hp out of a four-cylinder engine, which is a 6.1-litre turbo changed V6108 engine built in-house by Kubota.

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Engine

While the stated horsepower is 170 plus an additional five horsepower boost in PTO and transport operations, our independent DPS test managed to get a maximum of 142hp at the PTO shaft after power losses through the transmission, which was the stated PTO horsepower. Not bad for a tractor which was fresh out of the box and had only been run for few hours.

To meet the strict Tier 4 final European emissions standards, Kubota has stepped up to the mark with a mix of exhaust treatment systems on the M-7 series: a combination of EGR (exhaust gas recirculation); DPF (diesel particulate filter), which effectively scrubs out pollution in the exhaust gases and uses a burn cycle to clean the filter; and SCR (selective catalytic reduction), which injects AdBlue into the hot exhaust gases, transforming them into harmless water and nitrogen.

The advantages of using multiple systems is that emissions are even cleaner than required and fuel and AdBlue usage is lower depending on how the tractor is used, allowing the 38-litre AdBlue tank to go a long way between fills, as will the substantial 330-litre diesel tank.

The Kubota was hooked up to a Herron trailer with gross weight of more than 21 tonnes

Transmission

The KVT following the model denotes that the tractor uses Kubota Variable Transmission. This is essentially a tried-and-tested ZF auto power transmission that has been found in several other brands for some time now. This transmission is smooth and simple to operate.

With two effective speed ranges that can be set anywhere between zero and 20km/h and zero and 50km/h, the only difference is responsiveness and sensitivity of control.

The button to switch between ranges is found under the movement control joystick, which was a little tricky to find but makes sense when you know it’s there. The fact that the transmission will creep when the drive is engaged may be a slight disappointment for some, although not something that bothered me as it allows the operator to inch on the brake pedal.

Movement of the tractor can be controlled via the foot pedal or the joystick on the right-hand armrest. Without any need to switch modes between the two, the joystick is simply pushed forward or backwards to control the movement speed.

It was great to see buttons on top of the joystick to change direction as well as a left-hand shuttle lever. A cruise control speed can be set on the monitor and activated with a push of a button.

Serviceability

Servicing and daily checks are straightforward and easily carried out thanks to the large single-piece bonnet that can be opened without tools, giving clear unimpeded access from ground level. The air cleaner and cooling package sits at the front of the engine bay and, as you would expect, opens out for easy access cleaning, while all daily checks and servicing are carried out on the left-hand side of the tractor for ease for the operator.

Diesel and AdBlue tank filling points are found together beside the steps on the left-hand side of the tractor, making them convenient to top up; colour-coded caps hopefully prevent confusion. Stated servicing intervals of 500 hours for the engine and 1000 hours for the transmission sit in the middle of the range of the tractors I tested.

For peace of mind for new owners, Kubota offers one of the better warranties, which is a standard two-year/2000-hour comprehensive cover plus a further three-year/3000-hour driveline cover.

Brent Lilley’s fellow reviewer Tom Dickson checks out the impressive cab visibility and accessibility

In the cab

Access to Kubota’s four-post cab is easy with large single-piece doors on both sides of the cab. Once seated on the premium air seat, the cab feels light and open with good visibility all around thanks to the slim pillars.

The cab interior is noticeably quiet with minimal engine noise, although this could partly be down to the fact that, overall, the engine is quiet compared to other tractors.

The dash moves with the steering wheel when adjusted to suit the operator and is clear and well laid out using a combination of gauges and a digital screen to display vital information.

The radio and air-conditioning controls are found behind the driver towards the right-hand rear pillar, which for me is a little too far out of the way.

A fairly substantial lighting package offers six work lights on the cab to the front and four pointed to the rear, as well as a further six lights incorporated into the bonnet. Comfort levels for the operator are helped with two-point mechanical suspension as standard, but it’s good to see Kubota offer an option for full air-cab suspension on its premium model tractors.

Up front is a linkage under the front axle, which effectively carries it all and moves the pivot point further back behind the axle, suspending it on two hydraulic rams.

This is a useful setup, which allows the amount of travel to be adjusted or locked completely, as well as three settings for firmness of the front suspension.

Controls

Controls are largely found on the right-hand armrest. It’s logically laid out with subtle colour coding to help identify controls associated with each other. It’s great to see the main movement control joystick also incorporate buttons to control the direction of travel, cruise control, rear linkage height, and toggle switches for two sets of rear remote valves.

A secondary cross-gate joystick controls two further sets of remotes and would be a great feature to control a loader, if fitted. Fingertip toggle switches are used to control any further sets of remote valves.

The hand throttle slider, 4WD and diff lock buttons are conveniently located on the armrest, as are two preset engine rpm buttons that can easily be set up on the monitor.

While the PTO on/off switch is found on the armrest, one of the few controls on the right-hand console levers to select the four PTO speeds. This is good to see, as it offers more speed choices than many of the other tractors.

The 12-inch touchscreen monitor (connected to the right armrest) was one of the largest monitors of the line-up, putting a wide variety of information and adjustable settings at the operator’s fingertips. In terms of operation, it is relatively easy to use.

The screen is split into four separate areas – one large and three smaller. Information displayed on each area is customisable simply by choosing an icon at the bottom of the screen, then tapping where you want that info to be displayed.

There are camera inputs for the screen so live images can be displayed, and it is fully ISOBUS compatible. This means screens for ISOBUS implements can also be displayed without cluttering the cab with monitors.

It’s great to see that the Kubota M7-171 is GPS and auto-steer ready. A scroll wheel with an integrated enter button is found on the side of the monitor, offering secondary controls for times when a touchscreen isn’t suitable.

The controls are colour coded and logically laid out on the right-hand armrest

Hydraulics

The Kubota M7 premium model tractors run a closed-centre load-sensing (CCLS) system with a pump rated to a maximum output of 110L/min. For the first time this year, DPS independently checked the hydraulic flow rate from a single spool. The Kubota recorded a max of 88L/min, and while that is lower than most, I still feel it is more than adequate for most tasks.

With three sets of remotes at the backend, there is an option for more. These are arranged horizontally with two sets on the left-hand side of the top link and one on the right-hand side. It’s good to see these are logically colour-coded to match the corresponding coloured controls in the cab.

It was slightly disappointing that the remotes cannot be reassigned to other controllers as they can on many other tractors.

As you would expect, the flow rates and how they function can easily be adjusted in the hydraulics display on the screen. It was also good to see load-sensing power beyond valves as well as hydraulic trailer brakes and a high flow return.

Linkage

Ease of operation and functionality is important with the rear linkage on any tractor, and Kubota has done well here. Cab controls are easy to use and include an up and down button on the joystick and a height adjustment dial on the armrest. The controls are always live with no need to activate them before using the linkage.

Maximum and minimum height draft control can be easily adjusted through the touchscreen monitor, making it easy to set them up for the task at hand. The lift capacity is stated at 9000kg at the hook ends. Hitching the tractor to a 3.5m Sumo Trio was straightforward with Cat 3 hook-end arms and easily adjusted stabilisers.

External buttons to control the rear linkage on both rear mudguards, as well as a control for one remote for the top link and a PTO stop button, also help when hitching implements. Up front, a Zudiburg front linkage has a respectable lift capacity of 3500kg, which is more than ample for most tasks. Front PTO was also fitted to the tractor tested.

Performance

While something the size of a 3.5m Sumo Trio cultivator wouldn’t normally be matched with a 170hp tractor, it was certainly a good way to showcase the low-down lugging power of the Kubota.

With the Sumo in the ground and the forward speed target setup on the transmission, the forward speed increased as the engine rpm was dropped down to a sweet spot around 1300rpm, which is great for economics.

A power droop setup on the monitor allows this point to be set and the tractor to maintain maximum productivity.

A loaded Herron trailer with a gross weight of more than 21 tonnes was another excellent test of the Kubota’s transport applications. The Kubota got the trailer moving with smooth progression through the transmission and was able to bring it to a stop with the aid of the hydraulic trailer brakes.

The tractor was a little unbalanced with this amount of weight and the ride quality was compromised.

As mentioned earlier, the dyno results highlighted the low-down torque of the tractor. Spot-rate fuel usage was measured on all tractors at 1000 PTO rpm while on the dyno and the Kubota sat at 36.9L/h or 0.260L/hp/h, which is slightly higher than some other tractors.

The bottom line

Overall, I was keen to see what the Kubota had to offer as a new contender in this horsepower range. I was impressed at how the company has stepped up to the mark.

High-quality and tried-and-tested components have been used throughout, offering peace of mind to potential owners. There is excellent visibility from the cab and an impressive amount of functionality has been combined with ease of operation for an enjoyable operating experience.

It was great to test the Kubota and will be exciting to see the continued expansion of the brand.