Heavy-duty transmissions for tactical and logistic vehicles

Transmissions play a decisive role in the performance profile of wheeled and tracked vehicles, especially when used off-road on construction sites, off-road and in the military. At its production facility in Szentgotthárd (Hungary), US transmission manufacturer Allison Transmission presented its transmission assembly and selected examples in practical tests.

In motor vehicles, transmissions distribute engine power to the axles and wheels as required. One of the most important tasks of manual transmissions is to translate the power characteristics of the engine to the current tractive power requirement. Users expect an uninterrupted supply of tractive power from the drive, as modern automatic transmissions offer today. Experienced drivers remember the pain of double-clutching and intermediate throttle, which required a lot of power and diverted their attention from driving the vehicle to shifting gears.

Automatic transmissions can not only supply nearly uninterrupted power, but they also relieve the driver, who selects the appropriate driving programme before critical situations and can then concentrate on speed and lane selection. This means that difficult tasks can be more easily mastered, especially off-road driving, and the operator has a less fatiguing experience. In addition, automatic transmission enables continuous driving at high speeds over long periods of time and contributes to efficient driving.

Transmissions for wheeled and tracked vehicles

Allison Transmission’s portfolio of transmissions covers civilian and military vehicles, ranging from roughly 11 or 15 tonne wheeled vehicles with a typical drive power of around 250 kW to 63 tonne tracked vehicles with 1,100 kW drive power. The modular transmissions are assembled in their basic configuration with customer-specific additions (for instance, a retarder, or power take-off) on production lines and then completed according to customer specifications.

Gearboxes are typical dual-use goods. They are basically constructed in the same way for civil and military applications. Differences arise from compliance with military standards. Allison generally designates transmissions for wheeled vehicles in military applications with the designation SP (Special Purpose); while steering/braking transmissions (cross-drive) for tracked vehicles have an X in the designation.

Transmissions for civilian wheeled vehicles in Europe are manufactured in Szentgotthárd while military wheeled vehicles in the Europe, Middle East and Africa region (EMEA) defence sector receive transmissions from Allison plants also in Hungary and in Chennai, India. Transmissions for tracked vehicles are supplied all over the world from the company’s main plant in Indianapolis (USA).

Features of automatic transmissions

Allison automatic transmissions are characterised by the torque converter, which uses a fluid to transmit the engine power according to the tractive force requirement without wear. This centrepiece of the transmission provides high torque even at standstill and enables smooth starting even under heavy loads. The sustained high torque then ensures powerful acceleration. In conjunction with Allison’s ‘Continuous Power Technology’, power transmission is uninterrupted with 6 to 10 gears. As a result, the vehicle drives smoothly even on rough terrain or with a full load. At the same time, shocks in the drivetrain are avoided, which benefits service life. Accordingly, maintenance is largely limited to fluid and filter changes.

Test drives

Attached to the assembly plant is the Allison Customer Experience (ACE) centre, where, since 2012, vehicles with fully automatic Allison transmissions can be experienced and tested on an area of six hectares. From an observation terrace, the view extends over a test area with roads, paved and unpaved paths, freely drivable terrain and a steep track – enough different surfaces to feel the suitability of the respective transmission in practice. There was a choice of transmissions in heavy and medium trucks, in medium military vehicles and in a high-speed rally vehicle.

In the ACE centre, 14 on-road and off-highway vehicles, including three military vehicles and one rally vehicle, were on display for comparison. Allison began by demonstrating the difference between an automated transmission, in which a dry clutch is shifted automatically, and a fully automatic transmission with a torque converter. The red Scania P340 with torque converter sprinted off, quickly and clearly leaving its white competitor of the same design behind.

The civilian trucks with total weights between 10 and 41 tonnes were equipped with 3000 and 4000 series transmissions. Guided by experienced drivers, visitors were able to push the off-road vehicles to their limits. The fully automatic transmissions made it possible to concentrate on the choice of speed and lane. Even the inexperienced test drivers managed to keep the vehicles on the difficult tracks and avoid getting stuck.

The 11 tonne Spanish-built URO VAMTAC 4×4, the lightest of the three military vehicles displayed, was equipped with an Allison 1000 transmission that supplies 202 kW to the wheels. At 17 tonnes and 265 kW, the Hungarian-produced Komondor RDO 3221 4×4 used a 3200 SP transmission. The French/Czech Titus 6×6 was the heaviest military vehicle shown, at 23 tonnes and had the most powerful engine, rated at 370 kW. With its large wheels, it was the only vehicle capable of overcoming all terrain obstacles on the course. Self-driving was not possible in military vehicles.

The Iveco Powerstar EVO 3.2 Dakar Truck attracted the most attention, with an unladen weight of 8.5 tonnes and a high-powered 735 kW engine, coupled to the Allison 4000 transmission. The rally vehicle needs a lot of power in difficult terrain and high revs for high speed in forgiving terrain. While the driver had his hands full getting the truck around the course at top speed, the transmission automatically provided the appropriate tractive force and speed at the axles, thus enabling top performance.

Current applications

Allison is currently involved in numerous projects in the field of wheeled and tracked vehicles, as shown in Table 1.

	Table 1 – Allison Military Transmission Overview
	Transmission	Input Power	Input Torque	Weight class	Application(s)
Wheeled vehicles	1000 SP; 2000 SP	254 kW	895 Nm	15 tonnes	VAMTAC
	2500 SP	244 kW	705 Nm	11 tonnes	JLTV
	3000 SP	336 kW	1,695 Nm	28.5 tonnes	Bóbr-3
	4000 SP	597 kW	3,200 Nm	n.k.	n.k.
	4500 SP	375 kW	2,400 Nm	20 tonnes	Zetros
	4700 SP	n.k.	n.k.	n.k.	Astra
	4800 SP	600 kW	3,000 Nm	41 tonnes	Boxer
Tracked vehicles	X200	298 kW	n.k.	18 tonnes	FV 432, FNSS ACV
	3040MX	600 kW	n.k.	37 tonnes	CV90, Warrior, Borsuk
	4040MX	750 kW	n.k.	42 tonnes	CV90 Mk IV
	X1100	1,120 kW	n.k.	45-63.5 tonnes	M1A1, M1A2 Abrams, Krab, Firtina

 

Canada will receive more than 1,500 off-road 8×8 Zetros trucks from Mercedes-Benz equipped with 4500 SP transmissions from 2025 as part of the Logistics Vehicle Modernization. A similar truck participated in the demonstration in Szentgotthárd. The 4700 SP transmission from the same series is installed in the 8×8 Astra trucks that Iveco Defence Vehicles (IDV) supplies to the Romanian Armed Forces from its Romanian plant. The delivery of almost 3,000 trucks has been delayed due to the coronavirus crisis but could be completed in 2025.

Like its predecessors, the Boxer 8×8, currently produced in large numbers by ARTEC for the UK, Germany and Australia, is equipped with the powerful 4800 SP transmission. Originally intended for an engine output of 560 kW, the transmission now manages an input power of 600 kW. In Poland, the amphibious 4×4 reconnaissance vehicle Bóbr-3 will be equipped with an Allison 3000 SP transmission. The 16 tonne vehicle is powered by a 204-kW engine and is scheduled for delivery from 2026.

Transmission production in Szentgotthárd

In early October 2024, Allison invited a group of trade journalists to the Allison Transmission Hungary plant in Szentgotthárd, near the border with Austria, to demonstrate transmission production and experience Allison transmissions in real applications.

Allison has been assembling transmissions for civilian wheeled vehicles in Szentgotthárd since 2000. Following modernisation in 2011, customer-specific adaptation of the transmissions is also conducted there. The U-shaped assembly line is designed for the assembly of 3000 and 4000 series transmissions; assembly takes place on alternate days, depending on the order situation in a two-shift operation, with a third shift also possible during peaks in demand.

Components for gearboxes are delivered, with around three quarters of parts coming from the main plant in the USA, with the rest from suppliers in Europe. It takes just under three hours for a gearbox to be produced after ten main stations and to enter the final quality assurance stage. In a functional test, the gearbox is run in all operating states. It then goes into the leak test, where the gearbox is subjected to a pressure of 0.5 bar underwater. If the gearbox fails, it is dismantled and the fault rectified.

Each day, one gearbox is randomly selected for a tear-down audit. This gearbox is completely dismantled. During disassembly, all connectors are checked to identify possible errors/risks in the design or production. If defects are found, the same procedure is applied to the two gearboxes with neighbouring serial numbers. In the event of further defects, a total of 20 gearboxes are evaluated. Defect-free gearboxes are reassembled, and the day’s production is released for delivery. According to Allison, such quality defects occur two to three times a year.

In 2025, Allison Transmission in Szentgotthárd plans to produce 24,000 gearboxes. With three shifts, annual production could rise to 36,000 gearboxes.

Gerhard Heiming