Oshkosh recently delivered the last of 78 upgraded Medium Equipment Transporters (METs) to the UK Ministry of Defence (MoD) under an approximate GBP 16 million contract. The first of these upgraded trucks have already been used to transport additional British Army armoured vehicles and equipment out to Estonia.
Under a June 2020 post design services (PDS) amendment to the original Wheeled Tanker contract of 2003 and following on from delivery of a ‘proof of concept’ example, from June 2021 Oshkosh converted a further 77 Wheeled Tanker tractor units into a dual MET/Wheeled Tanker configuration. At the time, MET was designated Light Equipment Transporter (LET).
Oshkosh sub-contracted MiVi of Leyland to carry out the conversion work on the tractor units. Broshuis BV of The Netherlands, the supplier of the in-service trailer, was sub-contracted to carry out the necessary work on the trailers, with the work done in the UK by Broshuis’ partner, John Hudson Trailers of Bawtry. Work on around 30% of trailers was carried out at remote MoD-controlled sites including Mönchengladbach, Germany, by MiVi. Conversion work per tractor unit was around 150 hours, with conversion work per trailer around 50 hours. Work to fit 11 of the tractors with a Plasan-supplied armour package from MoD storage added around 300 hours of work per vehicle.
The project to convert up to 118 of the 357 in-service Wheeled Tanker tractors into the LET configuration dates back to around 2012, and the UK MoD’s desire for a new LET capability dates back even further to at least 2008. Earlier still, during 2004 as an Urgent Operational Requirement (UOR) for Afghanistan, an initial six Wheeled Tanker tractors were converted to work with the in-service LET trailer in the Interim Light Equipment Transporter (I-LET) role. This was necessary since the Seddon-Atkinson 6×4 LET tractor in service at the time lacked the required level of mobility and was unable to accept add-on armour.
The Seddon Atkinson fleet had been delivered from 1992 and was originally coupled to a Trailmaster three-axle stepframe low loader trailer. Trailmaster ceased trading shortly after delivery and owing to ongoing problems with these trailers, a replacement was purchased earlier than planned from Broshuis during 2004. Broshuis supplied 99 of these 44,000 kg payload trailers.
To operate in the UOR I-LET role, modifications to the Wheeled Tanker tractors were limited. They primarily centred on lowering the fifth wheel height and fitting 14.00 R 20 tyres to replace the standard 16.00 R 20 tyres. When coupled to a Wheeled Tanker tractor, the trailer payload was limited to 19,000 kg, due to the axle and fifth wheel load ratings of the tractor unit.
Post-Afghanistan the six armoured tractor units essentially stood idle. Four were to be converted as part of the current LET project, with the remaining two originally designated to be cannibalised for spare parts. However, following examination by MiVi, under a standalone PDS task the two ‘donor’ vehicles were instead designated to be refurbished and returned to service as standard unarmoured Wheeled Tanker tractors.
FLET to CAVP and Beyond
By 2009 the British Army’s Seddon Atkinson LET replacement programme (Future Light Equipment Transporter (FLET)) had been cancelled for reassessment. Two submissions had been received for the requirement – Oshkosh with a Wheeled Tanker derivative and MAN with a HX Support Vehicle derivative. Oshkosh was selected as preferred bidder prior to cancellation. Later that year, in September the UK MoD announced that Frazer-Nash Consultancy had been appointed to oversee production of the Combined Articulated Vehicle Programme (CAVP) User, System and Service Requirements Documents (URD/SRD). Superseding FLET, CAVP was ultimately expected to call for a common tractor unit in a requirement that in addition to delivering a FLET capability would include a replacement for the General Support Tanker (GST), plus a small number of specialist transporters for the Royal Air Force (RAF). The GST requirement is believed to remain outstanding.
However, in 2013 and with CAVP effectively stalled and the Seddon Atkinson LET having been declared obsolete in 2012, a Wheeled Tanker tractor unit was shipped to the United States as Government Furnished Equipment (GFE) during 2013 and LET-specific modifications were carried out. This work was MoD-funded as a Wheeled Tanker PDS task. The vehicle was returned to the UK later in the year and undertook a short series of confidence trials at the British Army’s Combat Service Support Training and Development Unit (CSS TDU), Long Valley.
Modifications to the tractor unit, which would later be applied to all 77 follow-on conversions, were based around the rear two axles and their TAK-4 independent suspension. The original 9,000 kg-rated coil sprung units were replaced by an 11,800 kg-rated hydro-pneumatic suspension setup with variable ride height. This modification allows for a maximum king pin load increase from 9,000 kg to 15,000 kg, and a permissible gross combination weight (GCW) increase from 44,000 kg (design rating) to 68,000 kg, at which the vehicle would operate as Special Type General Order (STGO) Category 2, with payloads of up to 44,000 kg.
Other modifications were essentially limited to larger brake actuators, to cope with increased weights, a new hydraulic pump to allow for a trailer-mounted winch to be powered by the tractor unit, and uprated propshafts. Two key MoD requirements for the uprated tractor unit, which were met, were that it has UK Type Approval, and that it retained its Wheeled Tanker tractor capability, and so able to serve in both the Wheeled Tanker and LET roles. A modified tractor unit can switch between roles, with driver input limited to using a single switch to inform the central tyre inflation system (CTIS) of the vehicle role, due to optimum tyre pressures being role-specific.
As an interim LET-type solution, 78 Broshuis trailers were converted by Broshuis during 2012-2013 to Modified Light Equipment Transporter (M-LET). These were then able to operate with a standard Wheeled Tanker tractor, albeit at a reduced 19,000 kg payload. Broshuis’ modifications centred on raising the swan neck height by 170 mm. Other work included a full strip-down and re-spray, air, electric, and braking system modifications and upgrades, as well as new ramps. Additionally, a winch is fitted to the swan neck of some trailers for the handling of casualty vehicles. Following upgrade, trailers were returned with a new five-year chassis warranty. Service entry for the M-LET standard Wheeled Tanker tractor combinations occurred during 2012-2013. It is these trailers that are being used under the current LET project, with additional work limited to the addition of two new tie-down points, and the upgrade of existing ones.
Prior to the delivery of the new LET capability, the majority of the UK MoD’s 19,000-44,000 kg lifts were performed by civilian contractors, with Oshkosh 1070F HETs available for the tactical movement of these loads.
MTVR/Wheeled Tanker
The Wheeled Tanker tractor unit is a derivative of the Oshkosh Medium Tactical Vehicle Replacement (MTVR). The MTVR was designed to meet a US Marine Corps (USMC) requirement and the type is the Marines’ standard vehicle in its weight class. Between 2001 and 2013 around 11,400 MTVRs were delivered to the USMC. The UK MoD became the first export customer for the MTVR when in March 2003 Oshkosh Truck was awarded the Wheeled Tanker contract.
Photo: Shaun Connors
The Wheeled Tanker tractor is a modified MK23 MTVR with a wheelbase shortened by 330 mm and the cab extended by 660 mm. Automotive changes include the Caterpillar C-12 six-cylinder diesel uprated from 425 hp to 445 hp (317 kW to 332 kW) and upgraded to meet EURO 3 emissions regulations. The 7F/1R Allison HD 4070P automatic transmission of the standard MTVR is replaced by a 6F/1R ‘wide ratio’ Allison HD 4560P unit.
Valued at approximately GBP 160 million for initial vehicle acquisition and support over 15 years, the Wheeled Tanker requirement called for 218 Close Support Tankers (CSTs) (fuel) with a 20,000-litre capacity; 82 × Tactical Aircraft Refuellers (TARs) with a 15,000-litre capacity, and 48 CSTs (water) with an 18,000-litre capacity, and additionally a contract option for an additional nine CST (water) was exercised. All tanker trailers were supplied by Magyar of France. Wheeled Tanker deliveries began in February 2005 and were completed in November 2006. The contract was extended to March 2023 to enable completion of the LET/Wheeled Tanker conversion and will be extended sole source to Oshkosh out to 2030 for Wheeled Tanker and LET trailer support.
Shaun Connors
