Both pit type and low profile scales offer a choice in platform material. Platforms may be constructed from concrete or steel plate or, in some cases, wood. The material you choose will depend somewhat on personal preference as well as the way you use your scale. The initial price of a concrete scale will be a little less than an equivalent scale with a steel platform yet when you add in the cost of the concrete and finishing labor, it will exceed the cost of its steel decked cousin. Concrete also requires a curing time which will delay the use of the scale but concrete is less slippery in wet weather, is not affected by most chemicals, doesn’t rust, requires little or no maintenance and provides years of service. Steel decks are usually constructed from checkered plate which gives extra traction in wet weather. In general, if your application calls for heavy loads and lots of them, concrete is the preferred material for the scale deck.

Scales are available in either full electronic or electromechanical models as well. Full electronic scales are directly supported by multiple load cells typically numbering 6 to 12 cells or more depending on the length of the scale. Electromechanical scales are supported by a series of bearings attached to ends of levers mechanically summing the forces applied to the scale platform. A summed force is applied to a single load cell. Most truck scales today are of the full electronic type simply because they are easier and less expensive to construct. Electromechanical scales are still available from some manufacturers and offer some unique advantages. The use of a single load cell makes the scale less susceptible to damage from lightning and they require less power to operate which means a simple battery operated weight indicator can be used when power is not available. Disadvantages of the electromechanical scale include the need for periodic maintenance or repair due to the wear in the bearings of the mechanical lever structure and higher initial cost. The full electronic truck scale has a lower initial price and is easier to work on since there is no complex lever system. The individual load cell signals of a full electronic truck scale must be summed to provide the total weight signal to the weight indicator. Summing of the load cell signals normally takes place within one or more junction boxes typically located at or near the scale. Because the outputs normally differ from load cell to load cell, it is necessary to make compensating adjustments which may become lengthy depending on the method used.

Finally, when choosing a truck scale, consideration should be given to the method of weighbridge restraint used. The weighbridge or scale platform must be constrained so that it does not slide off the supporting structure as a truck enters of leaves the scale. Although there are a number of ways of accomplishing this, the two most common are check rods and bumper bolts. Bumper bolt systems consist of an adjustable rod or bolt or similar device attached to the weighbridge and positioned such that it strikes the adjacent foundation or lower structure preventing further movement of the scale weighbridge. This is an effective and simple means of restraining the weighbridge but, to work properly, it must be periodically adjusted to maintain the proper clearance between the adjacent lower structure or scale foundation and bolt head. As the scale is used, this gap changes and must be adjusted to keep the restraint system operating properly. The check rod type of restraint system is a long thin rod that attaches the weighbridge to the surrounding structure preventing lateral movement of the weighbridge. The ratio between the length of the rod and its diameter is quite large allowing the rod to flex without affecting the accuracy of the scale. Unlike bumper bolts, check rods do not wear and therefore require little or no maintenance.

Truck scales are available in a wide range of sizes. Platform widths from 8 feet up are available while lengths often exceed 100 feet. You should select a platform size that is not only sufficient to weigh the trucks you currently have but large enough to weigh the trucks you may use in the future. Generally, widths of 11 to 12 feet are preferred for trucks used on the highway. Not only are scales of this width easier to ship, but they are approximately the lane width of many of our nation’s highways. Scales of greater width are available but are more expensive both in initial cost and in the costs associated with testing. Choose a length that is long enough to weigh the largest truck you anticipate weighing in the future. Remember, adding an extra 5 feet or so to the length seven years from now will be much more expensive than purchasing that extra length initially. Also, keep in mind that the scale must fit within the area you have allocated for the scale remembering to allow for a straight approach and departure from the scale preferably equal in length to the scale platform itself. It’s better to be a little large than too small.

Like platform size, weighing capacity should be selected based on your current and anticipated needs. There are two capacities associated with truck scales. The first, nominal capacity, is the total measurable load that can be distributed over the scale platform. Most truck scales have nominal capacities of 200,000 pounds which is more than sufficient to weigh highway trucks. Selection of the nominal capacity is normally not of concern since it is typically great enough to handle all but the most extreme loads.

As you can see, a lot of thought must take place when considering the purchase of a truck scale. If you are considering or looking for a used truck scale, you need to consider all the topics that were mentioned earlier. You also need to consider the fact that in most cases with a used truck scale, you are buying a scale with very little if any warranty and you are buying a scale that has had thousands and thousands of pounds of equipment driven over it for years. There is also the outdoor element factor that must be considered.  Finally, many times a specific concrete foundation must be poured to fit the used scale.  All of these factors must be considered and factored into your total cost of ownership.

The RoughDeck AX uses four corner-mounted, FM-approved load cells, with the cells recessed into the frame channels for protection. Also included is a signal-trim summing board enclosed in a stainless steel, NEMA 4X junction box for any necessary corner corrections. The RoughDeck AX comes pre-trimmed; so corner corrections should not be necessary.

Load cell cables are enclosed in conduit through the main channels, and held down with replaceable cable ties near each corner, eliminating the possibility of cable damage in portable applications.  Because of the possibility of foot and load cell damage from forklift tines, the scale should always be lifted from above with chains through the eyebolts when setting up the scale. The adjustable carbon steel captured ball feet are used to assist with self centering the scale as vehicles drive on.  The four access ramps for the RoughDeck AX come equipped with a heavy duty treaded top plate.

The scale must not be loaded beyond its capacity, even momentarily. Do not select a site where overweight loads would have to maneuver to avoid crossing the platform. Avoid areas where the scale might receive damaging side impacts or shock damage. Avoid areas where water may damage a scale not meant for a washdown environment. The interface cable between the scale and the indicator must be protected against crushing, cutting, or moisture damage. If the chosen site has such potential dangers, some method of protection, such as running the cable in conduit, will be necessary. In operation, the scale must be level within 1/4 inch.  Either choose a site where the ground is close to this standard to avoid excessive shimming, or modify the ground at the chosen site to meet this standard.

The CLC rating is not a measure of weighbridge strength or rigidity, because weighbridge deflection is not measured in the NTEP test. It is irrelevant if the load weighbridge sags 1/10th of an inch, or 10 inches, as long as the scale weighs within the accepted tolerance. The scale’s CLC weight rating passes in either case. A high CLC rating could be given to an extremely flexible deck sitting on load cell mounts which are capable of accurately handling the side loading resulting from a severely sagging weighbridge.

The Rice Lake SURVIVOR® truck scale line boasts a 45 ton (90,000 pounds) CLC rating. With most legal highway weight limits being a fraction of Rice Lake’s rating, owners of a SURVIVOR scale can expect a long lifespan through the most rigorous weighing processes of two million weighments or more. NTEP provides a set of procedures for the uniform testing and evaluation of weighing equipment. For a truck scale to be NTEP-certified Legal-for-Trade, the entire truck is weighed, not just a single axle or group of axles. The SURVIVOR series is approved for up to 270,000 pound full scale capacity with a 90,000 pound CLC rating, earning NTEP certification up to 14 feet wide. NTEP has additional guidelines for truck scales, such as the required length of approach ramps. For clarification on your state’s requirements, contact a qualified dealer who can help you determine the best site for your scale to meet those guidelines. For North Carolina, contact Central Carolina Scale in Sanford NC.

Truck Scale Indicator

Cardinal’s 225 Navigator features transflective technology which allows the 225’s display to be viewed under any lighting conditions from direct sunlight to total darkness. One-inch-high (25 mm) weight characters make viewing easy. View up to 3 scales with total weight simultaneously with the optional dual scale input board; no special software is needed with Cardinal 225 Navigator digital weight indicator.

Entering, viewing, and storing truck names is easy with the 225 Navigator’s convenient Truck ID menu.  Complete alphanumeric descriptions for truck and material prompts make storing and recalling tare weight values quick and simple.

Cardinal SCA Truck Scale Load cells are fabricated from stainless steel to provide the ultimate in protection when caustic, corrosive or wet environments are encountered. Load cells are hermetically sealed for absolute water protection (IP68). Each load cell is furnished with stainless steel load buttons on each end, and a 9m integral multiconductor cable secured by a strain relief seal.

Concrete Deck
While a concrete deck needs approximately 21 to 28 days to cure, it offers greater resistance to rust and corrosion from road salt and generally requires less maintenance than steel decks, helping to extend the life of the scale. A concrete surface also yields better traction with rain and snow. Because of their design, concrete decks distribute the load over a wider area than steel decks.  Rice Lake SURVIVOR® Series concrete deck truck scales are poured at the job site and typically have cure strength of 4,000 PSI at 28 days. The concrete is reinforced with steel rods and a minimum of two wide-flange main beams and seven wide-flange beams below. The Rice Lake SURVIVOR® concrete deck design incorporates galvanized steel sheets working in conjunction with I-beams to ensure that concrete remains above the neutral axis of the weighbridge.

Many low cost models contain concrete below the neutral axis. Concrete below the neutral axis increases tension causing the deck to crack and eventual weighbridge failure.

Steel Deck
A steel deck typically involves less initial cost – there is no investment in concrete or the labor to pour it. A steel deck scale weighs less, which makes it easier to move or relocate if needed. It can be fully operational within a day, reducing production downtime.  Rice Lake SURVIVOR steel deck truck scale designs are consistent with the design standards used by the American Association of State Highway and Transportation Officials (AASHTO) and the federal Road and Bridge department. The diamond checkered steel tread plate is supported by wide flange structural I-beams positioned longitudinally with traffic flow.

Many other manufacturers use lighter beams, C-channels in the middle of the bridge or space beams further out from the center of the module to reduce the cost of the scale. Over time, this type of bridge can bow or dimple, causing inaccuracies in weighments, scale downtime and eventually complete failure.