The science behind the next generation of tilting three-wheelers

Patents reveal work on a three-wheeled TMAX

By Ben Purvis

The ‘Leaning MultiWheel’ (LMW) arm of Yamaha’s model range looks set to grow with the development of a new model derived from the TMAX 560. Sliding into the range between the NMAX-based Tricity 300 and the MT-09-powered NIKEN, the new model’s existence is betrayed by patent applications that reveal a new front suspension system which moves away from the telescopic fork-based design used on Yamaha’s other LMWs.

The suspension itself is derived from an existing design that was used by Norwegian firm Brudeli for the KTM-based 654L and 625L ‘Leanster’ trikes. The layout was developed by Brudeli back in 2004 and Yamaha bought the patent rights in 2017, at the same time as they started work on this TMAX-derived machine.

The system itself is based on car-style double-wishbone suspension, with two coil-over shocks. The upper mounting bracket for the shocks remains upright as the rest of the bike leans, and the geometry is designed to encourage the bike to return to an upright position. The new element that Yamaha have added is a brake disk and caliper fitted where the suspension mount tower attaches to the main tilting section of the bike. It means the suspension can be locked into position, removing the need for a stand when the bike is stationary. Yamaha’s patent also includes the provision

The layout was developed by Brudeli in ’04

for an electric actuator that can help control the bike’s lean angle, but the document says this component isn’t vital.

The design has been previewed on the MW-Vision concept vehicle which Yamaha revealed at last year’s Tokyo Motor Show. While that was a roofed trike with a car-style seating position, the tilting system and front suspension layout was virtually identical to the arrangement seen on the TMAX patent.

The rear section of the bike is identical to the existing TMAX 560, sharing the same 562cc, DOHC parallel twin engine and twist-and-go transmission. That means an A2-licence legal 47hp at 7500rpm and 41lb.ft of torque at 5250rpm, a big increase on the Tricity 300’s 28bhp but still a long way short of the NIKEN’s 116bhp performance figure.

Most of the frame is also similar to the TMAX’s, just as the Tricity 300 shares many of its components with the NMAX, and that should help give economies of scale to keep production costs – and showroom prices – down. Given that Yamaha’s mediumterm business plan, covering 2019-2021, included a silhouette image of a sporty-looking three-wheeled scooter using the Brudeli front suspension, sitting alongside the Tricity 155, Tricity 300 and NIKEN in its proposed LMW range, it seems this new bike isn’t far away.

Norway’s Brudeli used the design on their Leanster

The patent shows it is out with the NIKEN’s front end Tower of power The TMAX 560 engine is clear to see, along with the existing bike’s swingarm and rear frame section. System overload An electronic actuator that’s governed by the on-board computer can accurately control the lean angle. Standard springing Leaning front suspension does without the NIKEN telescopics. Instead there’s a double-wishbone layout. Look no stands An extra brake disc and caliper is fitted to the leaning mechanism to lock it in any position, so it won’t fall over when parked. Yamaha showed a similar system on this concept