Military tactical vehicles have for the most part remained similar to their commercial cousins since their introduction during the First World War. In most armies they were often exactly like the commercial versions though painted in green or sand colours with some military ‘options’.
This paradigm has changed and has done so relatively quickly with many tactical trucks taking on a new form. Some of the differences are visually apparent while others are submerged in the equipment itself. All these differences were driven by what many see as a new reality in the way warfare is occurring now and in the future. The key changes to tactical vehicle design encompass three areas: crew protection, off-road mobility, and availability/reliability.
Tactical trucks, like their commercial counterparts, have traditionally been ‘soft skinned’ i.e. unarmoured. They were seen in land forces doctrine as support vehicles that generally would operate behind the forward echelons. In fact, as trucks they were never ‘safe’ and were often targeted by the enemy and employed in combat. The ambush of convoys was an accepted tactic and particularly common facing insurgents as in during the US intervention in Vietnam between 1965 and 1975. Field units routinely added improvised armour to trucks. Today the ‘hardening’ of trucks has become, for many armies, standard. This need to provide protection to the crew and load is a direct response to the resurgence of the mine and the appearance of the improvised explosive device (IED) particularly in the Iraqi and Afghan theatres since the start of the century. Fluid operations and the targeting by insurgents of logistics and support units equipped with soft skinned vehicles coupled with a heightened sensitivity to military casualties, particularly within Western powers, found armies adding purpose-built protection kits for light, medium, heavy and even line-haul (the movement of cargo between bases or logistics centres) trucks.
The US military, responding to the growing targeting of its logistics units as demonstrated during operations in Iraq, launched an accelerated programme for the development and fielding of cab protection kits that could outfit existing trucks. For example, the Low Signature Armoured Cab (LSAC) was developed by Stewart and Stevenson (now BAE Systems) for the US Army’s FMTV (Family of Medium Tactical Vehicles). In addition, Add-on Armour (AOA) Crew Protection Kits (CPK) were introduced for the Oshkosh-produced M-915 Heavy Equipment Transporters. The US plan now will have the majority of its tactical trucks equipped with protection, including both ballistic and enhanced mine blast resistance. Touring any US Army motor pool, it is now difficult to find a soft skinned tactical truck.
Many other countries have followed suit and the industry has responded, incorporating innovative integrated and removable protection in their military designs. Mercedes Benz’ Unimog, Zetros, and Actros vehicles all offer off-the-shelf armoured protection using welded steel enhanced with composite panels and spall liners. Some armoured configurations are nearly impossible to distinguish from the ‘soft’ version. Typically the protection levels guard against small arms impact and assure crew survival against mine/IED blast. The involvement of so many countries in the Afghan theatre has prompted many other armies and vehicle manufacturers to include retrofit and production protection to their military vehicle lines. Renault Trucks Defence, Iveco, Volvo, Rheinmetall-MAN Military Vehicles, ZIL and others all offer armoured logistic trucks. In addition, armour companies like Plasan, Ceradyne, QinetiQ and TenCate continue to develop and refine protection solutions more suitable for trucks. The Qineti-Q Blast Pro add-on mine protection, Blast Ride seats, and LAST appliqué armour each address specific threats to the vehicle and crew. Plasan has similarly teamed with vehicle firms like Oshkosh and Tatra to design and offer the ECP-59 Armour Protection Kits (APK) for the US Marine’s MTVR (Medium Tactical Vehicle Replacement) vehicle family, HMETT (Heavy Expanded Mobility Tactical Truck) Wreaker and other models. The APK, which includes cabin protection and armour plating of the cargo bed as well as suspension upgrades and air-conditioning, is a typical example of the depth of these efforts.
Enhancing the off-road mobility of military trucks by taking advantage of new technologies in suspension systems has also been a recent focus. The impetus for the adoption of these improvements is partly in response to the added weight of the protection packages (the APK adds 3045 kilograms/kg (6700 pounds/lbs). Another factor is for supporting vehicles to stay off roads. The idea of this is that doing so makes it harder for opponents to predict traffic patterns and, thus, where to place mines. A second consideration is that having the option of moving more freely means tactical trucks can more closely and effectively support the forward ground manoeuvre. However, doing so though places them at risk of being attacked themselves which adds to the need crew protection.
Improving traction on soft and sandy surfaces can allow traverse of even the toughest terrains—muddy fields, desert sand dunes, climbing grass-covered embankments and fording rivers. Previous seen as the ‘nice to have’ option of tire pressure control or CTIS (Central Tire Inflation Systems) can enhance the off-road characteristics of military trucks. In CTIS, controls in the cab allow the driver to inflate, deflate and adjust the tire pressure for different load and operating conditions. CTIS will even allow continued movement if there is minor tire damage by providing a continuous supply of air.
The most significant mobility improvements have been the result of wheeled suspension system advances. Oshkosh’s TAK-4 was one of the first of these to be widely applied. Jennifer Christiansen, vice president of business development operations at Oshkosh Defence, explained to Armada that “(the) TAK-4 independent suspension system delivers 400mm (16 inches/in) of independent wheel travel to deliver exceptional mobility in places where off-road terrain and unpaved roads dominate. It also delivers improved ride quality, allowing troops to arrive ready for their missions.” A further advance is the TAK-4i intelligent independent suspension system developed for the company’s JLTV (Joint Light Tactical Vehicle) equipping the US Army and Marine Corps. She further explained that “the TAK-4i intelligent suspension system uses high pressure nitrogen gas (HPG) to deliver 508mm (20in) of wheel travel, has advanced shock absorbers, and can be raised and lowered using interior controls. It offers a 70 percent increase in speed.” TAK-4 is used on the MTVR, OM-ATV (Mine-Resistant, Ambush-Protected All Terrain Vehicle), the US Army’s Palletized Load System and Logistics Vehicle System Replacement (LVSR), all of which are manufactured by the company.
The hydro-pneumatic suspension seems to offer significant benefits and is being pursued by a number of companies. VSE in the Netherlands has refined hydro-pneumatic suspension, and introduced advanced electro-hydraulic steering for truck rear axles. Their spokesperson suggested that “these systems provide extra cargo capacity, improved the manoeuvrability and superior distribution of wheel loads,” adding that “our systems are on over 50000 trucks.” Hendrickson Defence has a full line of high pressure gas-based suspensions including integrated systems like the Hydro-Pneumatic (HHP) Suspension that provides superior ride quality, handling, stability, durability and ride height adjustment specially needed by the severe conditions in which military vehicles must operate. Their HPAS can replace existing mechanical components to offer improved ride and stability while achieving a 50 percent weight and 60 percent reduction in volume.
Meanwhile, Horstman Defence’s HydroStruit combines both spring and damping functions in a lightweight self-contained design. It incorporates variable height suspension, rebound end stop damping and automatic compensation for spring force environment and temperature changes. Mark Bowles, engineering director at the company, said “the key suspension trade-offs require maximum wheel travel, lowest mass and high reliability in punishing environments. Basically, it’s all about power density. Using nitrogen gas at very high working pressures as the spring allows for a very space-efficient design, and also delivers a progressive spring rate to reduce impact shocks.” This not only contributes to better crew comfort but also assures load stability and better handling. In addition to allowing traverse of more difficult terrain and doing so at higher speeds these more effective suspensions can also positively influence the reliability of other vehicle subsystems. The shocks of a rough ride are transmitted through the vehicle body to the crew but also to electronics and other vehicle components. This contributes to their potential failure. Reducing the frequency and level of shock that occur in movement favourably increases their reliability.
Another approach is General Kinetic Engineering Corporation’s Active Shock Management (ASM) product. Their system consists of electronic controls, a variable orifice damping valve and patented ride control software algorithms. That ASM can be applied to existing shocks and dampers to convert them to “semi-active” making them significantly more effective allows upgrade to existing systems. LORD Corporation’s Controllable MR Suspensions use another design and are based on Magneto-Rheological (MR) technology to move fluids in the system. These integrated units continually react to vehicle and terrain conditions in micro seconds adapting the suspension to the situation. This provides improved dynamic stability.
The third area of change in military tactical vehicles is in improving maintenance and repair, and increasing reliability and operational availability. For military equipment, particularly in combat operations, “availability” is of primary importance. Having equipment ready and able to be used for a mission when needed can determine mission capability and success. It drives what the unit can do and the resources it has at any time to undertake an assigned task. A combination of new design approaches, innovative maintenance and repair procedures and application of technologies, some previously widely adopted and proven by commercial truck fleets, have allowed availability levels approaching and even exceeding 90 percent even in rough combat conditions.
For the military the primary consideration when a piece of equipment breaks down is how quickly it can be repaired and back in service. Military aviation has faced this challenge for many years as it is vital to keep the always limited number of aircraft ready to fly. To do this military aviation has adopted a trouble-shooting and corrective action technique that focuses on identifying the faulty components and replacing them on the spot. Combat vehicles were one of the first ground platforms to adopt this approach. So-called ‘power-pack’ designs, as utilised by Kraus-Maffei Wegmann in their Leopard-2 Main Battle Tank and Marder infantry fighting vehicles, integrate the engine, transmission, drives, fuel pumps, and cooling into a single compact unit. Every effort is made to simplify the connections to allow them to be quickly ‘unplugged’ and reinstalled. This has now been adopted in tactical trucks as well.
The recognition of the need to both simplify and reduce the time needed to undertake not just repair but also routine preventative maintenance is being adopted for tactical vehicles. As an example, Mercedes Benz’ military truck lines have all their service and scheduled maintenance points readily accessible simplifying and reducing the time to complete these checks and procedures. This marks recognition of the vital importance of preventive maintenance.
Technology is also providing another tool with the potential to revolutionize vehicle maintenance and repair. Called Vehicle Health Monitoring (VHM) or Integrated VHM, it takes advantage of the increased digitalization of vehicle systems to gather usable data from sensors placed at various key operational functions. These collect data on everything from engine speed, suspension play, mileage, use hours and more all of which is sent to and stored by a HMU (Health Monitoring Unit). This stored data can then be downloaded by maintenance to gain a near real-time ‘snap-shot’ of the usage and status of each of the vehicle subsystems. Using this collected data it is possible to estimate wear and conditions stressing the various subsystems. By including a wireless transmitter it is possible to automatically send and download this data even from a remote location.
The primary objective of IVHM is to allow early identification of faults to allow responsive corrective action through the use of diagnostics and prognostics (predictive diagnostics). Added benefits include improving availability by scheduling servicing based on usage and actual wear, improving reliability by gaining a more thorough understanding of the overall health of the vehicle and components, and reducing unnecessary maintenance time and costs. By monitoring, recording and analyzing usage data it is possible to understand the loads and stresses placed on the vehicle. This can now be coupled with GPS (Global Positioning System) location information to offer further insights into the environment in which the vehicle has operated. Bringing all this information together it is possible through prognosis programmes that draw on accumulated histories of similar vehicles and components to often not just identify a failed part but to predict the possibility of future failure. Doing so permits repair and replacement to be accomplished proactively. This significantly reduces the possibility of suffering a failure during a mission. In addition, it permits more efficient maintenance and repair by allowing the replacement of components during scheduled service before they fail.
Oshkosh’s Command Zone integrated control and diagnostics system is a computer-controlled, electronics technology that diagnoses all major vehicle networks. The company programme office explained: “The backbone of Command Zone is advanced multiplexing technology. This allows vehicle components to work in concert, streamlining diagnostic and troubleshooting … it allows real-time access to critical vehicle information via command and control networks, laptops, on-board display screens or hand-held personal digital devices locally or remotely.” The system is included in the JLTV and can be offered in other tactical trucks.
IVHMS is also offered by North American Industries as a ‘plug-in’. Their 35PC0C ‘black box’ is an off-the-shelf unit that can accept data from on-board sensors to “enable the maintainer to schedule maintenance based on actual performance and conditions, rather than when a component fails.” In fact, the move toward open architecture networked vehicle systems allows pre-emptive diagnostics to extend beyond the automotive systems to include virtually any equipment on the vehicle.
Many armies are realising the potential benefits of embracing IVHM. For tactical trucks based on commercial models like those offered by Mercedes, DAF and Mack lines, IVHM and on-board vehicle diagnostics are already standard equipment. Here the military users are able to take advantage of the extensive adoption of this technology particularly in the management of large truck fleets and heavy/construction equipment. The implications toward enhancing the operational availability of tactical platforms, as already realised commercially, are huge and even more critical for the military. By predicting problems before they occur, it can be possible to correct them when the system is not on a mission or coordinated to be performed during a break in the action. Doing so keeps the vehicle performing its role when needed and increases confidence in the number of assets that will be at hand at any time. This is a critical advantage in planning for and conducting military operations where often, particularly with deployed forces, assets are limited. In addition, by reducing the possibility that a vehicle might breakdown operating in hostile areas or in proximity to combat eliminates the concern that a recovery and rescue, possibly under fire, might be necessary.
Advances in computing speed, increased memory and integration of functions like geographic positioning, networking and communications are opening new possibilities. One of these within the realm of possibility is further refinement of diagnostics and prognostics. The capability to automatically predict a component failure and report it, thus allowing pre-emptive corrective action, is easily foreseeable. A failing system can be identified in flight and reported to the maintenance unit allowing them to have the part in hand to replace it immediately at the first opportunity.
Computing power coupled with fully adjustable suspensions, often using a nitrogen-filled system, will also allow the ‘ride’ of the vehicle to be refined based on the contours of the terrain encountered, the load and the vehicle speed. This will permit higher cross country mobility with higher payloads and greater safety and stability. The next step may well be to convert tactical vehicles to autonomous control, removing the crew entirely. The US Army has planned technology demonstrations of driverless convoys in June 2016. Oshkosh Defense has undertaken its own development as well called the Terra-Max Unmanned Ground Vehicle which has demonstrated not only an individual vehicle, but also convoy operations.
It is not clear when or if driverless tactical vehicle, at least for logistics, will become commonplace, but it is certain that the tactical truck is assuming a new form. Though these changes remain mostly hidden from view, the capabilities that they have introduced to the tactical truck are significant. Further, these have facilitated major changes in the manner in which these vehicles are employed and supported. The implementation of these changes is still unfolding so it will be interesting to watch how each military will respond and ultimately the benefits that will be gained from these new technologies.