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M970 5,000 Gallon Semitrailer Refueler
Overview
ManufacturerThe Heil Company
Production1980 or earlier[1]
AssemblyAthens, Tennessee
Body and chassis
ClassLarge Semi-trailer truck
Body styleTanker Semi-trailer truck
LayoutOver and Underwing Refueling
RelatedM-967, M-969
Powertrain
EngineLombardini 11 ld 626-3
Dimensions
Length366 in (9.3 m)
Width96 in (2.4 m)
Height104.5 in (2.65 m)
Curb weight15,200 lb (6,900 kg) empty, 49,150 lb (22,290 kg) loaded
Chronology
PredecessorM-131 Series
SuccessorNone

The M970 Semi-Trailer Refueler is a 5,000-U.S.-gallon (19,000 L; 4,200 imp gal) fuel dispensing tanker designed for under/overwing refueling of aircraft. It is equipped with a filter/separator, recirculation system and two refueling systems, one for underwing and one for overwing servicing. The tanker is designed to be towed by a 5-ton, 6x6 truck tractor or similar vehicle equipped with a fifth wheel. The M970 can be loaded through the bottom or through the top fill openings. A ladder is provided at the front of the semitrailer for access to the top manhole, and a 4-cylinder diesel engine and pump assembly provides self load/unload capability. The body of the refueler is a 5,000-U.S.-gallon, single compartment, stainless steel tank. The chassis is of welded steel construction and is equipped with full floating tandem axles and a manually operated landing gear. There has been talk of retiring the M970, but a suitable off-road replacement has not been found. The Marine Corps also uses R-9 and R-10 tankers, but they are not capable of off road use. The M970 is a part of the "United States Marine Corps Maintenance Center - Albany, Georgia, USA - An Integrated Enterprise Scheduling Case Study" which is working to upgrade the Semitrailer for future use.

U.S. Marine Corps R-9, Non-Tactical Aircraft Refueler

The M967 and M969 versions are similar but are configured to carry vehicle fuels (gasoline, diesel). The M967A1, M969A1 and M970A1 versions relocate the top access ladder from the front of the tank to the rear.

Utilization

[edit]

The M970 can be used as a stand-alone fuel tanker, delivering fuel directly to aircraft on a flight line. The Semitrailer is also used in Forward Arming and Refueling Points (FARPs) delivering fuel to multiple nozzles for quick fueling operations at the front lines or beyond. This is generally used for helicopters, but can also be utilized with AV-8B Harrier II or with an Expeditionary Airfield (EAF). M970's were used to assist in loading the bladders for the Tactical Airfield Fuel Dispensing Systems (TAFDS) in the field as well.

Part of the TAFDS, the fuel bladders.

The M969/M969A1 is a self loading and unloading tank semi-trailer designed to carry and dispense fuel to other vehicles at Forward Arming and Refueling Points. The M967/M967A1 is similar but it is designed to only carry bulk fuels between fuel terminals and depots and is not equipped to dispense fuel to other vehicles.[2]

Specifications

[edit]
U.S. Marine Corps M970

All models of the M970/M970A1, M969/M969A1 and M967/M967A1 share a common basic chassis, motors, etc. The basic tank is a 5,000-US-gallon (19,000 L) baffled tank.

BASIC DIMENSIONS:

  • Length : 366 in (9.3 m)
  • Width : 96 in (2.4 m)
  • Height : 104.5 in (2.65 m)
  • Square : 244 sq ft (22.7 m2)
  • Cube : 2,126 cu ft (60.2 m3)
  • Weight: Empty - 15,200 lb (6,900 kg)
  • Weight: Loaded - 49,150 lb (22,290 kg)
  • Ground Clearance: M970 - 16 in (410 mm) / M970A1 - 19.5 in (500 mm)
  • Kingpin Height: 56 in (1.4 m)

FUEL CAPACITY:

  • 33,950 lb/5,000 U.S. gallons (19,000 L; 4,200 imp gal) highway
  • 25,800 lb/3,800 U.S. gallons (14,000 L; 3,200 imp gal) cross country
  • 20% maximum side slope wo/leakage: 5,000 U.S. gallons
  • 10% maximum longitudinal slope wo/leakage:5,000 U.S. gallons

FUEL DATA FOR 4-CYLINDER ENGINE TYPE : Diesel

GALLONS PER HOUR: 1.5 U.S. gallons (5.7 L; 1.2 imp gal) Self Onload - 300gpm Offload - 600 pgm

FORDING CAPABILITY: Can ford hard, flat bottoms. Depth depends on prime mover and semitrailer payload (fuel is lighter than water and will float) Without a fording kit the tanker can enter 24 in (610 mm) of water safely.

ELECTRICAL SYSTEM: 24 volt, negative ground, powered by prime mover; pump motor, 12 volt, negative ground, 65 amperes

BRAKES: Air, powered by prime mover

EQUIPMENT OPTIONS: Kits: Vapor Recovery, Recirculation System, Two Refueling Systems - for Underwing and Overwing Servicing

Engine

[edit]

The M970 and M970A1 models use a Cummins Onan four-cylinder inline diesel engine with air cooled compression ignition, producing 27.5 hp (20.5 kW). Though older models will be equipped with the Lombardini 11 ld 626-3. It has a fuel tank of 3.2 us gal.

Tires

[edit]

The M970 uses 11:00 R20 tires with two tires per side per axle in the rear

Models

[edit]

The M970 series includes the following base models:

Model Description
M970 5,000-U.S.-gallon fuel tanker
M970A1 Same as the M970, but has 3 inches (76 mm) more ground clearance

The M970 is towed by the following Prime Movers:

Model Description
M-931 Tractor-trailer truck
M-932 Same as the M-931, but with a 15,000-pound (6,800 kg) winch on the front
M-818 Tractor-trailer truck
MTVR (MK31) An MTVR tractor
M-931 5-Ton Tractor
M-818 5-ton tractor

Safety

[edit]

Equipped with Filter Separator System which removes water and sediment from fuel; has emergency cut off valve for fuel dispensing; has shear pins and a spring valve in the underwing refuel hose should the hose separate from the hose reel while in use, preventing fuel from spilling into the deck; equipped with Purple-K fire extinguishers.

See also

[edit]

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

M970

View on Grokipedia
from Grokipedia
The M970 is a 5,000-U.S.-gallon (18,927 L) fuel-dispensing semitrailer designed primarily for underwing and overwing refueling of military aircraft. Towed by a 5-ton, 6x6 truck tractor equipped with a fifth-wheel hitch, it features a single-compartment stainless steel tank, a 4-cylinder diesel engine-driven pump for self-loading and unloading, and a filter/separator system to ensure clean fuel delivery. Introduced into U.S. Marine Corps service on March 14, 1978, the M970 supported aviation operations by transporting and dispensing jet propellant (JP) and diesel fuels across highways, secondary roads, unimproved terrain, and cross-country environments, with a fording depth of 30 inches (76 cm). Its key specifications include a length of 366 inches (9.3 m), width of 96 inches (2.4 m), height of 104.5 inches (2.65 m), curb weight of 15,200 pounds (6,895 kg), and gross vehicle weight of 49,150 pounds (22,305 kg). The M970's design incorporated dual refueling systems, a recirculation capability for , and provisions for both top and bottom filling, enabling versatile operations in field conditions. It could perform refueling/defueling as well as ground vehicle fueling, with filtered dispensing to meet standards for contaminant removal. Notable components included full-floating tandem axles for mobility, manually operated , and a for access to the top , enhancing and in austere settings. With a planned 30-year until 2008, though remaining in limited use beyond that date, the M970 has been largely succeeded by the MK970 variant—a -adapted commercial tanker with similar 5,000-gallon capacity plus 3% expansion space—which continues to provide enhanced ruggedness for modern tactical as of 2025.

Development and Production

History

The M970 semi-trailer refueler was introduced in the late as part of the U.S. Marine Corps' efforts to modernize support systems. It was fielded with a follow-on in 1994.

Manufacturer and Production Timeline

The M970 was manufactured by various companies. Production of the M970 commenced in the late , as evidenced by its entry into U.S. on March 14, 1978. Initial batches were built under government contracts, including those for the U.S. Army and Marine Corps, such as DAAE07-85-C-J044 and DAAE07-89-C-J020, which supported early assembly and integration of key components like the auxiliary and pumping systems. The production timeline spanned the 1980s, aligning with heightened U.S. military procurement during the era's defense buildup, though exact output quantities remain classified or not publicly detailed in available records. Planned for a 30-year , production shifted following the end of the in 1991 toward sustainment, upgrades, and limited new builds into the . Later variants continued into the . No major shifts in locations or subcontractors are documented for the base M970, though later MK970 replacements were manufactured by Heil Trailer International.

Design and Features

General Configuration

The M970 is a tanker designed as a tactical fuel-servicing unit, featuring a single-compartment tank mounted on a welded with full-floating tandem axles for transporting and dispensing fuel primarily for underwing and overwing refueling. This configuration allows the tanker to integrate seamlessly into operations, where it is towed by 5-ton 6x6 tractors such as the M939 series, equipped with a fifth-wheel kingpin assembly for secure coupling. Structurally, the M970 incorporates a manually operated with adjustable legs and removable shoes to provide stability when detached from the towing vehicle, alongside an undercarriage assembly that includes spring seats and cross tubes for effective load distribution during transit. The at the front ensures robust attachment to compatible prime movers, enabling the to navigate both on-road and off-road environments typical of convoys. Additionally, a provides access to the tank's sealed , supporting maintenance in field conditions. The tank's construction utilizes corrosion-resistant , which forms a protective oxidation to withstand exposure to fuels and harsh operational environments, ensuring long-term durability for fuel storage and transfer. This material choice, combined with integral baffles within the tank, minimizes sloshing and enhances stability during movement. For self-loading capabilities, the M970 includes a diesel engine-driven system, allowing independent fuel intake without relying solely on external equipment.

Refueling and Auxiliary Systems

The M970 features a primary refueling setup designed for efficient dispensing to , including underwing and overwing connected to specialized . The underwing system utilizes a 2½-inch, 50-foot with a single-point dispensing equipped with deadman control and breakaway fittings, enabling high-pressure delivery suitable for such as the AV-8B Harrier II. In contrast, the overwing configuration employs a 1½-inch, 50-foot with an overwing dispensing , optimized for helicopters and vertical-lift operations. These are stored on electric-rewind reels with quick-disconnect fittings, facilitating rapid deployment and secure connections during field refueling. Auxiliary systems enhance fuel integrity and operational reliability through a recirculation mechanism and integrated filter/separator assembly. The recirculation system allows to be cycled through the filter/separator, meter, and hoses to remove , , and contaminants, ensuring quality maintenance during storage or prior to dispensing; this process supports fuel sampling and prevents degradation in the 5,000-gallon tank. The filter/separator, constructed of aluminum with 15 filter elements and 5 water stripper elements, automatically drains accumulated via sump valves while monitoring differential to detect clogs. Self-sufficiency is achieved via an onboard 4-cylinder that drives a assembly, enabling independent loading and unloading without external power sources. This setup supports self-loading through bottom tank adapters or top fill openings, with a float valve automatically halting flow to prevent overfilling. Operational monitoring is provided by an array of gauges on the control panel, including a capacity indicator for levels, and meter inlet gauges for system integrity, and a with meter for flow rates. These instruments allow operators to track performance in real-time, ensuring safe and precise refueling for like helicopters.

Specifications

Dimensions and Capacity

The M970 semi-trailer refueler measures 366 inches in length, 96 inches in width, and 104.5 inches in height, allowing it to integrate with standard prime movers while maintaining compatibility for transport in C-130 aircraft or rail cars. Its empty weight is 15,200 pounds, providing a lightweight for efficient towing, while the fully loaded weight reaches 49,150 pounds when carrying its maximum payload, ensuring structural integrity under operational loads. The M970 has a fuel capacity of 5,000 U.S. gallons (18,927 liters), with the entire volume usable for dispensing without a dedicated reserve, supporting bulk storage and transfer for operations. It is compatible with , JP-5, and fuels, enabling versatile refueling of fixed-wing and rotary-wing . Load distribution is optimized through a centrally located fifth-wheel kingpin and balanced tank compartments, promoting towing stability when paired with 5-ton trucks like the M939 series and minimizing axle overload during highway or off-road transit.

Engine and Propulsion

The M970 semitrailer refueler is equipped with a Cummins Onan Model DJC-MS4118W diesel engine, a four-cylinder, four-cycle, air-cooled unit with valve-in-head configuration that delivers 27.5 horsepower at 2400 RPM. This engine, with a displacement of 120 cubic inches and a compression ratio of 19:1, serves as the primary onboard power source for independent fuel handling operations. It drives a three-inch high-pressure centrifugal pump via a direct shaft connection, enabling self-loading, unloading, bulk delivery, and recirculation of fuel without reliance on the towing tractor unit. The pump achieves flow rates up to 300 gallons per minute and operates at pressures around 65 PSI, supporting efficient transfer in underwing or overwing aircraft refueling scenarios. The engine's integration into the M970 involves mounting it as a modular assembly on the frame, secured with capscrews and locknuts, positioned near the rear for optimal access to the . Electrical systems connect through an for charging a dedicated battery and a that powers auxiliary components, such as the starter and , ensuring reliable operation during extended dispensing tasks. for the engine is drawn from a dedicated using low-pressure pumps and filters, with excess injection fuel recirculated to maintain efficiency; the engine operates on meeting Federal Specification VV-F-800, typically No. 2 grade above 32°F. While specific runtime on internal reserves is not quantified, the design allows continuous operation limited by availability and load, with guidance for issues like excessive consumption due to overload or contaminated systems. Maintenance for the emphasizes regular intervals to sustain performance, including changes and filter replacements every 600 operating hours, servicing every 3000 hours or upon power loss, and clearance adjustments every 500 hours. capacity is 6 quarts without filter or 6.5 quarts with, maintaining pressures between 20 minimum and 40 maximum when warm. These procedures, detailed in preventive checks and services (PMCS), support operational durations aligned with mission needs, with the engine's air-cooled design and integration minimizing downtime in field environments.

Tires and Chassis

The M970 semitrailer features a dual-wheel tire configuration mounted on axles to enhance stability and load distribution during transport. Each axle supports dual 11.00 x 20 pneumatic s, designed as military nondirectional cross-country types compliant with MIL-T-12459 specifications, providing improved traction on varied terrains including off-road conditions. A total of eight tires are in use across the two axles, with an additional carried onboard, and recommended inflation pressures are 40 psi for cross-country and operations or 60 for hard-surface roads to optimize performance and durability. The is constructed from welded , forming a robust frame that supports the 5,000-gallon and associated components while ensuring structural integrity under heavy loads. It incorporates a tandem overslung suspension system with semi-elliptic multi-leaf springs and rods, rated for rough terrain operations and providing approximately 16 inches of ground clearance on applicable models such as TC-0843, TC-0844, and TC-103 through TC-178. This setup includes full-floating , each with a 25,000-pound load capacity, allowing the to handle expeditionary demands without compromising mobility. Mobility is facilitated by the M970's compatibility with 5-ton, 6x6 truck tractors equipped with fifth-wheel couplings, via a standard kingpin facility that ensures secure attachment and efficient ground handling. The assemblies, secured by 10-stud nuts torqued to 450-500 lb-ft, contribute to reliable performance, with the overall design emphasizing interchangeability of and tires with other 5-ton series vehicles for support in field operations. The reinforcements, including bumpers and brackets, are engineered for durability in forward-deployed environments, supporting the semitrailer's role in sustaining fuel over challenging routes.

Variants

Standard M970

The standard M970 is a 5,000-gallon (19,000 L) fuel-dispensing designed primarily for underwing and overwing refueling of , fielded by the U.S. in the late . It consists of a single-compartment tank with 3% expansion capacity, mounted on a welded with full-floating tandem axles and manual . The semitrailer is powered by a 4-cylinder air-cooled producing 27.5 horsepower, which drives a 3-inch high-pressure for self-loading and unloading operations. Key characteristics of the standard M970 include a 3-stage filter/separator system to remove water, solids, and other contaminants from aviation fuel during recirculation and dispensing. The system supports self-loading rates up to 300 gallons per minute (gpm) and bulk delivery rates up to 600 gpm, with dedicated hoses and nozzles: 50 feet of 2.5-inch hose on an electric-rewind reel for underwing refueling (including deadman control) and 50 feet of 1.5-inch hose for overwing operations. It is compatible with early 6x6 truck tractors, such as the 5-ton M818 or 10-ton M915 series, for towing on highways and secondary roads. Additional features encompass pressure/vacuum vents, a sealed manhole for top filling, a calibrated sight gauge, portable grounding rod, static reel, and spare tire carrier. Production of the standard M970 occurred in the late , with units distributed to U.S. Army units and U.S. Marine Corps motor transport battalions for aircraft refueling support. Initial distribution focused on active-duty forces, with the NSN 2330-01-050-5635 assigned for inventory and logistics tracking. While effective for its era, the standard M970 exhibited limitations in off-road mobility due to its highway-oriented and design, as well as a basic filter/separator that provided adequate but not advanced contamination control for evolving standards, prompting subsequent model improvements.

M970A1 Upgrade

The M970A1 upgrade was introduced in the to enhance the standard M970 refueler's performance in rugged terrain, primarily addressing limitations in ground clearance that hindered off-road mobility during refueling operations. Developed through U.S. Army and Marine Corps contracts, such as DAAE07-85-C-J044 and DAAE07-89-C-J020, the variant incorporated modifications starting with production models around 1985, as documented in early technical manuals. These upgrades were driven by operational needs identified in field evaluations, enabling better compatibility with expeditionary deployments while maintaining the core 5,000-gallon capacity for under/overwing refueling. Key modifications included a lengthened assembly and revised overslung suspension (H900-50 series), which increased ground clearance from approximately 16 inches (410 mm) in the base M970 to 19.5 inches (500 mm) in the A1 variant, improving for rough terrain navigation. The was reinforced with a higher-capacity (A21T-7CT7R-DW10A, rated at 25,000 pounds), featuring hangers and spring leaf components for greater durability under load. Additionally, the refueling system received updates, including the retention of the 3-inch high-pressure operating at 65 psi, along with an improved filter/separator assembly using 15 filter elements and 5 water strippers to handle contaminants more effectively. Other enhancements encompassed cam-type brakes with slack adjusters for superior actuation, an elastomeric drive coupling between the pump and engine, and relocated access features like a rear ladder for safer maintenance. These changes yielded significant performance gains, particularly in off-road handling, as the elevated clearance and integration of HMMWV-compatible runflat tires enhanced tractability when towed by like the M939 series, reducing the risk of undercarriage damage in austere environments. The upgraded and systems extended by minimizing wear from impurities and supporting higher flow rates (up to 300 GPM for self-loading and 600 GPM for bulk delivery), while enabling integration with newer fuel types like through better recirculation and deadman control circuits for contamination removal. Overall, the modifications improved operational reliability, with the A1 variant maintaining air transportability when empty on aircraft such as the C-130 and C-17. Adoption focused on the U.S. Marine Corps, where select M970 units (serial numbers TC-0843, TC-0844, and TC-103 through TC-178) were retrofitted or built to A1 specifications under the 1989 contract to meet expeditionary fuel distribution requirements. Further procurement in the early 2000s addressed shortages identified in Total Army Analysis studies. This rationale stemmed from Marine Corps evaluations emphasizing the need for versatile refuelers in forward-operating environments, prioritizing durability and mobility over the base model's design. The M967 semitrailer is a 5,000-gallon bulk haul tanker adapted from the M970 platform for transporting and transferring vehicle fuels, such as and diesel, to forward storage or distribution points. It features a single-compartment tank with 3% expansion capacity, a 4-cylinder , and a 4-inch centrifugal self-priming capable of bulk delivery rates up to 600 gallons per minute (gpm) and self-loading rates up to 300 gpm. Unlike the M970's aircraft-oriented systems, the M967 employs standard bulk couplings and lacks specialized dispensing nozzles, focusing instead on efficient transfer for tactical ground operations. The M969 semitrailer, also with a 5,000-gallon capacity, modifies the M970 design for direct fuel dispensing to ground vehicles, including trucks and armored units, in forward areas. It retains the same 4-cylinder and 4-inch as the M967, supporting bulk delivery at 600 gpm and self-loading at 300 gpm, but incorporates ground-level dispensing and shorter hoses optimized for automotive refueling at rates suitable for vehicle tanks. The tank shape and chassis remain similar to the M970, with adaptations primarily in the coupling and nozzle configurations to enable quick, on-the-ground refueling without aircraft-specific overwing or underwing equipment. Both the M967 and M969 share a production lineage with the M970, utilizing comparable components and falling under unified maintenance protocols in U.S. technical manuals. They serve tactical roles in supporting mobility by facilitating bulk transfer and direct refueling of vehicles in zones.

MK970

The MK970 (or AMK970) is a modern variant and successor to the original M970 series, introduced as a military-adapted commercial semitrailer refueler with a 5,000-gallon capacity plus 3% expansion space. It features enhanced ruggedness for tactical operations, including improved durability and compatibility with current U.S. Marine Corps truck tractors. The MK970 supports underwing and overwing refueling, bulk delivery, and recirculation operations, remaining in active service as of 2025 for expeditionary support. It addresses limitations of the legacy models through commercial design adaptations while maintaining MIL-STD requirements for purity and mobility across varied terrains.

Operational Use

Military Applications

The M970 semitrailer refueler plays a critical role in establishing Forward Arming and Refueling Points (FARPs), temporary facilities that enable rapid refueling of helicopters and fixed-wing aircraft in forward operating areas, including hot refueling during flight line operations to minimize aircraft downtime. These points support tactical aviation by delivering bulk fuel at rates up to 300 gallons per minute via compatible systems like the D-1 pressure refueling nozzle, allowing multiple aircraft to be serviced simultaneously in austere environments. In Marine Corps operations, the M970 facilitates both rotary-wing and fixed-wing refueling, integrating seamlessly with expeditionary logistics to sustain air missions without reliance on permanent infrastructure. The vehicle specifically supports key Marine Corps assets, such as the AV-8B Harrier II for and the UH-1N Huey for utility and command roles, alongside other aircraft like the CH-53D Sea Stallion, by providing JP-5 or aviation fuel directly to operational sites. During Operations Desert Shield and Desert Storm, M970 units were deployed with expeditionary forces, including the 7th and Marine Wing Support Squadrons (MWSS)-373 and -374, to refuel Harriers at bases like King Abdul Aziz and Hueys at Jubayl Naval Air Facility, as well as establishing FARPs such as FARP Foss at Manifah Bay for helicopter operations. The M970 was integrated into Marine Air-Ground Task Force (MAGTF) deployments through the mid-2010s, supporting expeditionary aviation in varied theaters by enabling quick setup and breakdown of refueling points. It has since been largely succeeded by the MK970 variant for modern operations (see Variants). Its primary advantages lie in high mobility across rough terrain, allowing deployment to remote or contested areas where fixed fuel depots are impractical, thus enabling sustained air operations for extended periods. This versatility was evident in Desert Storm, where M970s transported and dispensed 5,000 gallons per load to support rapid resupply chains for aviation units, reducing logistical vulnerabilities in dynamic combat zones. By prioritizing quick fuel transfer through its under/overwing dispensing capabilities, the M970 enhances overall mission endurance for supported aircraft without compromising operational tempo.

Operators and Deployment

The M970 semi-trailer refueler is primarily operated by the (USMC), serving as an essential asset for (ACE) and combat service support element (CSSE) logistics within Marine Air-Ground Task Forces (MAGTFs). It is organically assigned to Marine Wing Support Squadrons (MWSS), where each squadron maintains approximately 10 units for aircraft refueling and defueling, as well as to Motor Transport Battalions (20 units per battalion) and the 3rd Force Service Support Group (FSSG) Support Battalion (15 units) for over-the-road bulk fuel transport. These assignments support fixed-wing and rotary-wing operations across the Marine Aircraft Wings, including the 1st, 2nd, and 3rd MAWs. No documented exports of the M970 to NATO partners or other U.S. allies exist, confining its operational use to USMC inventories under Table of Authorized Material and Construction Number (TAMCN) D0215. The M970 has been deployed in major USMC operations, notably during Operations Desert Shield and Desert Storm (1990-1991), where it facilitated the receipt, storage, and distribution of over 81 million gallons of bulk fuel to support Marine aviation assets in the Persian Gulf theater. For instance, Marine Wing Support Squadron 374 (MWSS-374) employed 8 M970 units alongside other tankers to augment fuel delivery for fixed-wing squadrons and expeditionary airfield operations. As of 2014, training was conducted for motor transport personnel in units such as those under the to maintain operator proficiency for potential deployments, though the system has been succeeded by the MK970.

Safety and Maintenance

Safety Mechanisms

The M970 semitrailer incorporates an integrated filter/separator to safeguard fuel quality by removing solids, water, and other contaminants before delivery to , ensuring compliance with fuel purity standards. This , rated at 300 gallons per minute and 150 psi, features an aluminum tank with 15 filter elements and five second-stage water stripper elements, along with 15 fuses that monitor fuel purity and restrict flow if contamination levels exceed safe thresholds. A differential gauge (0-25 psid) provides real-time monitoring of filter restriction, alerting operators to potential issues that could lead to contaminated fuel transfer. Automatic and manual drain valves further support this by expelling accumulated water and sediment, with the automatic valve using a float mechanism to halt flow when water levels rise. Emergency features include automatic cut-off and fusible elements designed to prevent uncontrolled release during accidents or fires. The primary emergency , mechanically operated via a and cable system, closes the outlet in response to operator or structural compromise, while a fusible nut melts at elevated temperatures to trigger automatic shutdown. Additionally, shear pins integrated into the breakaway fittings on the 2.5-inch provide protection by shearing under excessive force, disconnecting the to minimize spill risks during refueling operations. A float in the sump automatically closes the 4-inch when reaches a predetermined level, averting overfill and potential spills. These mechanisms are supplemented by a deadman control on the dispensing , which halts flow if the operator releases the , enhancing operational . Fire suppression capabilities consist of two dry chemical fire extinguishers mounted in rear and side brackets. Grounding straps and studs, including static discharge reels, are mandatory for all fueling and maintenance activities to mitigate buildup, which could ignite ; these connect to approved grounds or to safely dissipate charges. Spill containment is addressed through procedural safeguards, such as placing grounded metal containers under drain points and requiring immediate cleanup of any leaks, with the tank's design incorporating surge baffles to reduce sloshing and structural stress during transport. The M970's safety mechanisms adhere to U.S. standards for hazardous , including requirements for explosion-proof like blowers used in purging operations, as outlined in MIL-B-7619. Overall, these built-in protections prioritize prevention of spills, fires, and structural failures, enabling safe operation in high-risk refueling scenarios.

Maintenance Requirements

The M970 semitrailer refueler requires structured protocols to ensure operational reliability, focusing on preventive measures to mitigate risks from handling and heavy-duty . These protocols, outlined in the U.S. Army's technical manual, emphasize operator-performed checks and higher-level services to maintain structural integrity and functional components. Maintenance protocols are similar for the M970A1 variant, with specifics detailed in the variants section. Scheduled maintenance includes daily pre-operation preventive maintenance checks (PMCS) to verify readiness before use. Operators inspect for fuel leaks around connections and tanks, damage to and wiring, structural of the towing vehicle connection and semitrailer frame, functionality including air pressure (maintained at 90-120 psi), vent operation, condition and (60 psi for hard roads, 40 psi for cross-country or sand), fire extinguisher accessibility, control panel gauges such as oil pressure (30-40 psi), battery charge, levels (4 gallons minimum), and conditions for cuts or kinks. Water must be drained from filters daily to prevent contamination. Quarterly services, conducted every three months, involve checking oil levels (6-6.5 quarts), replenishing , inspecting and servicing the air cleaner, and auxiliary components per lubrication order charts, cleaning surfaces with dry cleaning solvent, and servicing the piping strainer. Annual inspections target the tank interior and exterior for , dents, leaks, sediment buildup, and weld , including manhole covers and fusible vent caps; any damage requires reporting to unit for repair, such as dent correction with a or crack . Component-specific care addresses high-wear elements critical to safe fuel dispensing. Tires undergo daily and weekly visual inspections for , cuts, or flats, with lug nuts torqued to 450-500 lb-ft during servicing; while no fixed interval is specified, checks using a are recommended at 5% depth in storage to extend . Filter replacements occur based on performance indicators: the filter/separator primary element every 600 operating hours or when differential reaches 25 psi, the secondary every 3,000 hours, and filters every six months or if clogged, with air cleaner elements serviced when the red indicator band appears. Hose integrity tests involve pre-use examinations for cracks, kinks, or leaks, supplemented by soapy water application to air hoses to detect air loss; hoses are evacuated of before rewinding, and O-rings are replaced during reel to prevent failures. Durability is significantly influenced by fuel type, such as compliance with Federal Specification VV-F-800 for No. 1 or No. 2 diesel, which affects tank lining, pump seals, and filter longevity; improper fuels or contamination accelerate wear, while cold-weather water drainage and regular purging mitigate and sediment issues. support for the M970 integrates with U.S. supply chains, where spare parts like filters, gaskets, and probes (e.g., NSN 4930-01-013-7589) are procured through standard requisition processes, detailed in the repair parts manual TM 9-2330-356-24P. is mandatory, covering PMCS execution, , and repair procedures per the technical manual and DA Pam 738-750 for maintenance records; specialized tasks like tank purging require certification for personnel such as MOS 77F petroleum supply specialists to ensure compliance and safety.

References

  1. https://info.publicintelligence.net/18000297600.pdf
  2. https://www.dvidshub.net/video/901372/recirculation-operations-mk970-semi-trailer-refueler
  3. https://www.peols.marines.mil/Programs/Medium-Heavy-Tactical-Vehicles/
  4. https://www.army.mil/article/288871/motor_transport_operators_road_to_excellence_begins_at_fort_leonard_wood
  5. https://apps.dtic.mil/sti/tr/pdf/AD1003699.pdf
  6. https://www.liberatedmanuals.com/TM-9-2330-356-14.pdf
  7. https://www.globalsecurity.org/military/library/policy/army/fm/10-67-1/CHAP16.HTML
  8. http://armyquartermaster.tpub.com/Qm5200a/Fuel-Servicing-Semi-Trailers-196.htm
  9. https://warriorlodge.com/pages/m-970-semi-trailer-refueler
  10. https://info.publicintelligence.net/USMC-MotorEquipment.pdf
  11. https://www.chartertoconductor.com/wp-content/uploads/2020/02/1999-US-Army-DIRECT-TANK-VEHICLES-66p.pdf
  12. https://apps.dtic.mil/sti/tr/pdf/ADA119745.pdf
  13. https://static.e-publishing.af.mil/production/1/af_a4_7/publication/afpam23-221/afpam23-221.pdf
  14. https://www.xm381.com/TMs_Files/TM%2043-0001-31.pdf
  15. https://www.asafm.army.mil/Portals/72/Documents/BudgetMaterial/2001/base%20budget/justification%20book/opa1.pdf
  16. http://combatindex.com/store/tech_man/Sample/Trailers/2/TM_9-2330-356-14.pdf
  17. https://www.globalsecurity.org/military/library/policy/army/fm/10-67-1/CHAP24.HTML
  18. http://armyquartermaster.tpub.com/QM5094/M969-5-000-Gallon-Semitrailer-26.htm
  19. https://rdl.train.army.mil/catalog-ws/view/100.ATSC/604BCE7F-1507-42F1-9148-DD3ADB7CF09B-1528208078025/atp3_04x17wc1.pdf
  20. https://www.marines.mil/Portals/1/Publications/U.S.%20MARINES%20IN%20THE%20PERSIAN%20GULF%2090-91%20COMBAT%20SERVICE%20SUPPORT%20%20PCN%2019000314600_1.pdf?ver=2012-10-11-164140-887
  21. https://www.trngcmd.marines.mil/Portals/207/Docs/TBS/MCWP%204-11.6%20Bulk%20Liquid%20Operations.pdf
  22. https://www.usmcu.edu/Portals/218/U_S_%20Marines%20in%20the%20Persian%20Gulf%2C%201990-1991_Combat%20Service%20Support%20in%20Desert%20Shield%20and%20Desert%20Storm%20%20PCN%2019000314600.pdf
  23. https://www.dvidshub.net/news/150961/motor-transport-marines-train-become-semi-refueler-operators
  24. https://www.liberatedmanuals.com/TM-9-2330-356-24P.pdf
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