Choosing the Right Military Vehicle Torque Wrench - Blog

Service members need to trust their vehicles. Whether being used domestically or abroad, driven in convoy down I-95 or winding through the snowy peaks of Kandahar, military vehicles must be in top condition to meet the challenges of the road. Even more so than civilian cars or commercial trucks, military vehicles are subjected to tough, stressful environments, often far from a friendly service center.

In order to keep their occupants safe and the mission on track, military vehicles need to be built to last and properly maintained. And in order to accomplish these goals, you need to choose the right torque wrench.

Why Choosing the Right Torque Wrench Matters

Threaded fasteners, like screws and bolts, work best under specific load conditions. A stainless steel screw has a different failure point than a nickel-plated eye bolt, after all. Knowing this, military vehicle designers and engineers choose fasteners based on the load conditions they are expected to handle. So long as fasteners can bear the loads they are designed for, they will perform safely and reliably.

If torqued beyond the amount specified by the vehicle’s designers, however, your fastener will bear a greater load than it was rated for. Even if the vehicle is otherwise performing within safe operating limits (which, in emergent situations or difficult terrain, isn’t always the case), this added load can cause the fastener to warp, deform, shear, or otherwise fail. When a single fastener fails, it increases the stress on every fastener, potentially causing a cascading failure.

Not placing enough torque on your vehicle’s fasteners can cause similar problems. Fasteners which are not properly tightened may come loose under stress or motion, increasing the stress load on other fasteners. Loose fasteners rattling around a sensitive area, like an engine compartment, can cause ancillary damage in addition to the harm caused by their failure.

Who is Responsible for Torque Control?

Anyone who touches a fastener on a military vehicle—including vehicle operators, maintenance and service technicians, fleet management and procurement officers, certified civilian service centers, and vehicle manufacturers—is responsible for torque control. Military fleet maintenance is conducted at four levels: direct support, unit support, group support, and depot. Operators, technicians, and officers at each level must be equipped with appropriate torque control equipment and trained in its usage.

Regardless of how you interact with a military vehicle, you should concern yourself with achieving proper torque for three primary reasons:

To protect the personnel who will use the vehicle.
To reduce the cost and frequency of unexpected breakdowns.
To ensure compliance with regulatory codes.

If you are a servicemember and a military vehicle is placed under your care, you are responsible for properly maintaining it. Improper maintenance can result in a vehicle breaking down in a combat situation or an otherwise hazardous area, endangering the lives of your fellow servicemembers.

In addition, applying proper torque as part of a preventative maintenance program will reduce the number of unexpected breakdowns your vehicles experience. Not only does this increase vehicle availability, but it also reduces vehicle costs in multiple ways.

For one, fewer breakdowns reduces the number of expensive repairs required. It also extends the lifetime of the vehicles under your care, delaying replacement costs. For two, increased vehicle availability decreases the necessity of renting or leasing vehicles. Both means of cost reduction improve the efficiency of military operations and responsibly steward taxpayer funds.

Finally, if you are a servicemember, applying proper torque when maintaining vehicles under your care is mandated by the Uniform Codes of Military Justice. Chapter 10, Article 108 states:

Any person subject to this chapter who, without proper authority-

(1) sells or otherwise disposes of;
(2) willfully or through neglect damages, destroys, or loses; or
(3) willfully or through neglect suffers to be lost, damaged, sold, or wrongfully disposed of;

any military property of the United States, shall be punished as a court-martial may direct.

This means that if you fail to properly service vehicles under your care, you may find yourself on the wrong side of regulations.

These same considerations apply, in different forms, to civilian personnel involved in manufacturing or maintaining military vehicles. Achieving proper torque is equally essential to protect servicemembers, and while your budget may not be directly affected by breakdowns and repairs, your taxes still pay for them.

If the failure rate of vehicles you service or manufacture deviates significantly above the mean, fleet management officers may elect to change their service arrangements or purchase from a different vendor. While you are not subject to military justice, you are bound by the terms of your service or supply contract. High failure rates or poor service as a result of inaccurate torque values may place you in breach of contract.

How to Choose the Right Torque Wrenches for Military Vehicle Manufacturing

Assembling military vehicles requires power, precision, and versatility. Different assembly articles will have different requirements, but all fasteners will have designated torque values. Large vehicles—like tanks, mobile weapons platforms, and armored personnel carriers—will likely require high amounts of torque for structural bolts. In contrast, radio communications kits, GPS articles, and wiring components need small, precise amounts of torque. The needs of your factory depend on the type of components you intend to manufacture.

While precise needs differ, all manufacturers of military vehicles require certain capabilities, including:

Versatility
Repeatability
Efficient Documentation

Civilian vehicle manufacturers create extremely large orders of nearly identical vehicles. Military vehicle manufacturers create smaller, customized orders, sometimes of radically different vehicles. So, while speed and automation are emphasized in civilian manufacturing, military manufacturing demands systems which can rapidly adapt to the needs of different contracts.

Even when manufacturing different types of vehicles, repeatability is essential. Your factory is contracted to deliver vehicles which meet detailed specifications. As such, the tools you use to build your vehicles must deliver precise enough amounts of torque to meet specifications, every time.

Appropriate Torque Tools for Military Vehicle Production Facilities

For assemblies with low torque values, measured in lbf.in or smaller increments, manufacturers are well served by current-control electric screwdrivers. These screwdrivers control torque by measuring and adjusting voltage, making them highly adaptable and reliable. Models are adjustable on the face of the tool, which also displays relevant data for the tool operator. Brushless models are easier to maintain than screwdrivers with brush driven motors. Electric screwdrivers can be connected to automated systems, which allow for the rapid programming of complex fastening sequences.

For assemblies with higher torque values, measured in lbf.ft, manufacturers can turn to pneumatic pulse tools or hand-powered cam-over wrenches. Pulse tools fasten more rapidly than hand tools, making them suitable for high output operations. They deliver torque in a series of millisecond-long pulses, driven by compressed air. This delivery mechanism allows certain pulse tools to deliver up to ~330 lbf.ft of torque.

While pulse tools are faster and more powerful, cam-over hand tools are more accurate and thus better in terms of repeatability. The pulsing action of the pneumatic tool relies on a series of pulses, whereas cam-over tools deliver torque via continuous pressure. The continuous pressure allows for a more exact cessation of torque delivery, which cam-over tools accomplish with a “slip” mechanism. Some cam-over wrenches can deliver up to 90 lbf.ft of torque.

The need for repeatability goes hand-in-hand with the need for documentation. Not only must you build each vehicle to specification, but you must also be able to prove it upon request. Documentation is simplified by the use of automated control systems, which track fasteners as they are applied, then store and compile the data. These systems discover omissions, unfinished rundowns, and cross-threading as you work, allowing you to quickly fix assembly errors.

It is unlikely that a single series of tool will meet your facility's every manufacturing need. Instead, most military vehicle manufacturers are best served by various combinations of hand tools, power tools, and control systems.

How to Choose the Right Torque Wrenches for Maintaining Military Vehicles

Operators, technicians, and fleet management personnel must understand and correctly employ torque tools when adjusting their fasteners. To this end, fleet management and procurement officers should endeavor to understand what tools their various vehicles require. Likewise, civilian service centers that maintain and repair military fleet vehicles must be appropriately tooled to follow designated torque specifications for the vehicles they service.

The torque specifications for the vehicles under your purview will be listed in their technical manuals. To find the right tools, consider:

The amount of torque required: The amount of torque and specificity your vehicle requires depends on the vehicle and the type of service being performed. Small, frequent service tasks, such as tightening the oil drain plug or swapping out spark plugs require less torque and less specificity than larger, less frequent service tasks.
The specificity required: Consider the maintenance structure of your operation. What tasks are done at the unit level? Which are only done at the depot? Tool each unit with the equipment they need to accomplish their service responsibilities.
Available sources of motive power: Service or repairs expected to be done in the field cannot rely on DC or pneumatic power without special equipment and must depend on hand tools. Even at service centers with power sources, hand tools may still be necessary to reach fasteners in areas with smaller clearances.

After considering these factors, it’s time to select the right tool for the job. Various tools are best suited for various service tasks. Here are some common tools you may use.

In addition to these wrenches, you may find you need torque multipliers, geared devices which multiply the amount of torque a tool delivers, to handle the largest repairs. For instance, structural bolts on large, heavy vehicles, like tanks, demand torque values above those which can be delivered by hand or pneumatic pressure. Torque multipliers can be used with hand, electric, or pneumatic tools.

Finding the right torque wrench for military vehicle applications ultimately comes down to understanding the requirements of your application, selecting the wrench that best completes the job, and training your personnel to use it correctly. Whether you’re building or maintaining military vehicles, torque matters. Just as our country depends on our service members, our service members depend on your work to keep them safe.