- If the profile is 16” or less, then standard 8” high guide rails are satisfactory.
- If the profile is greater than 16”, then it must be treated differently.

Several standard offerings for a double-high rail system, with the top rail at 24” above the deck, reaches center-of-axle on a vast majority of over-the-road vehicles, but as the regulation states, “Any guardrail should extend to at least mid-axle height of the largest truck using the scale”. Therefore, it becomes the responsibility of the end user  to advise their sales person and the truck scale manufacturer on their actual height requirement based on the largest trucks to be weighed.

Keep in mind that rail systems provided on a typical truck scale are referred to as guide rails or rub rails or sight rails, but definitely not guardrails as MSHA chooses to define them. Therefore, most if not all, scale manufacturers do not claim that any of the guide rail systems attached to truck scales are fully MSHA compliant as there are simply too many application variables identified in the regulation and it really must be evaluated on a case-by-case basis.

Application unknowns such as speed of vehicle and angle of impact are specifically highlighted by MSHA as follows………“There are four parameters that should be considered in designing guardrails for a scale: the height of the rails (impact height); the speed of the vehicle while driving onto, over, or off the scale; the loaded weight of the vehicle; and the angle of impact.” MSHA sums it up quite well in their own wording when they state – “The mine operator should evaluate each of these variables for their operation and design accordingly” and – “There is no “one-size-fits-all” design for guardrails on truck scales”.

When it comes to truck scales with an elevation greater than 16”, the only way a customer is going to comply with all aspects of the MSHA regulation and it’s true intent is to hire a civil or highway engineer to design a proper guardrail system that is connected to the ground and designed to absorb or deflect the vehicle’s kinetic energy.  As MSHA states, “….a guardrail at least mid-axle height is intended to prevent the vehicle from driving through or over it.” Some customers are actually choosing to install the type of guardrail system that is commonly found along highways.

Breathing Room
Closed-bottom weighbridge designs with both top and bottom plates, typically using lighter weight components, create cavities that tend to hold moisture causing rusting of internal components. Rice Lake’s SURVIVOR® steel deck ATV truck scales feature an open-bottom design providing unrestricted airflow eliminating rust causing moisture buildup which accelerates rusting of internal steel and imminent scale failure.

Ultra Load Cell Protection
Load cell pockets that are welded or bolted to exterior I-beams allow excessive bending and flexing, causing damage to the weighbridge. Bumper bolts loosen and break. Check rods bind. Rice Lake’s SURVIVOR® series truck scales are designed with the load cell pocket integrated into the steel structure of the scale. The pocket is built inside the outer I-beam, offering a more durable, long-lasting load cell pocket. The SURVIVOR® series scales feature the G-Force™ self-checking mounting system, eliminating the need for check rods or bumper bolts.

Tough, Start to Finish
Harsh environments and corrosive materials can quickly deteriorate improperly finished truck scale components. Rice Lake’s SURVIVOR® series truck scales are steel shot blasted according to the highest industry standards to remove mill scale and surface imperfections. An asphalt emulsion undercoating is applied to all non-visible steel surfaces on all steel deck models to protect against moisture damage. High-performance epoxy primer and specialized hard-coat alkyd enamel is applied to all visible steel surfaces for a car-like finish that protects the scale from the elements.

1. What size scale do you need? a common answer is 11 ft x 70 ft.
2. Type of deck you need? Steel or Concrete
3. Type of scale interested in? OTR ATV SR PT or other model
4. Foundation already exist or do you need a new one?
5. Will the scale be Grouted or Shimmed?
6. Guiderails needed? How about the number of manholes needed? Clean outs? Yes or No
7. Is NTEP Legal for Trade required?
8. Finish upgrade needed like special paint?
9. What type of business will the scale be used in?
10. What type of trucks/equipment are using the scale? What is the largest vehicle weighed?
11. What is the axle configuration of vehicles being weighed? Single Tandem Triple Axle
12. How many trucks will be weighed per day?

Engineered with state-of-the-art robotics, Cardinal’s EPR+ Plus Truck Scale represents the culmination of 60 years of scale manufacturing experience. Available in impervious hydraulic or electronic load cell types, the EPR+ Plus’ durable baked-on, anti-corrosion powder paint stands the test of time. The legal-for-trade NTEP EPR+ Plus arrives fully-prepared for installation and includes DB75000 lb stainless steel load cells standard, which are factory assembled. All Cardinal load cells can withstand the weight of up to 150% of published load cell capacity. A wide selection of EPR+ Plus capacities, platform sizes, and types are available from Cardinal Scale. In North Carolina, customers rely on Cardinal dealer, Central Carolina Scale for both sales and service of Cardinal Scales.

Topside Housekeeping
Take a walk around the outside of the truck scale. Examine the entire deck, scale pit, foundation and approaches for any major structural or surface problems.  Scale owners with scales that have any deterioration need to fix them right away.   Any deck and approach repair is not merely cosmetic; those damages will have a negative effect on the scale.  Flaking rust and crumbling concrete falling into the pit will add maintenance costs now, but in the future they will reduce the scales’ usefulness.

Check Deck Clearance
If you have a pit scale, while still outside the pit, use a crowbar to check the weighbridge for free movement both with and without a vehicle on the scale. If binding seems to be an issue, check the pit wall-to-deck clearance. If clearance looks good all around, with no debris between the walls and the deck, you’ve done all you can topside. The binding problem is coming from below. Get your boots, gloves, hornet spray and lights, and get ready to head into the pit to look things over (or better yet, call your scale guy instead).  Just remember to check the oxygen level in the pit before you go down in the pit.

Keep it Clean Under the Truck Scale
The most common cause of incorrect weighments is debris in the pit binding movement. Clean all dirt from each component. Remember, even though most scales these days are electronic, they still have moving parts underneath. Load cells still need to be able to deflect through their capacity range.  We recall the story we heard recently of a customer requesting a service call to figure out what was causing his scale to weigh incorrectly. It was a pretty urgent situation because the scale had been red tagged and his whole business was shut down while they tried to figure out the problem. Well, the service guy soon discovered the problem – a single piece of gravel wedged between the weighbridge and side of the foundation!

To cut down on future problems, the scale owner needs to invest in flexible T-Grip or T-Strip molding. These moldings, while being flexible enough to work with the movement of the scale, will keep debris from causing problems and eventual damage to the truck scale. Depending on the scale design, the molding might only be necessary to cover the end gaps where the trucks enter and exit the scale. Scales weighing open trucks or messy operations will also need side molding to protect against spillage falling into the pit.

Load Cell / Lever Hybrids
When you have a hybrid lever scale converted to digital readouts with an S-beam load cell, you need to check a few more items during the inspection.  Replace any damaged load cell cables rather than splicing them. Cable splices are prone to moisture entry, leading to a new host of problems. For further moisture safeguards, replace j-box desiccant, or fill the box with Waterguard Gel.

If rodent or radio frequency interference are problems, switch to a cable offering both rodent protection and EMI/RFI protection.  We recommend the EL147RP load cell cable. For protection against rodents only, run the cable through conduit or in the Rice Lake SURVIVOR® Cable Armor.  Finally, get a complete scale calibration with certified test weights with proven accuracy.  Actually, your best choice is to set up a quarterly service agreement with your local scale company.  They have the expertise and equipment to keep your truck scale running smooth year round.  In central North Carolina, the choice would be Central Carolina Scale out of Sanford, NC.

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.

Binding is a common cause of inaccuracies. A rock as small as your big toe can become wedged between the foundation and deck.  Installing T-Strip molding between the deck and foundation can help keep debris from getting caught or falling down into the scale. Some above-ground scales have end cleanout plates that can be removed, allowing access to clean out debris that builds up on the foundation’s surface closest to the scale’s end.  The above examples are a great reason to contact an experienced truck scale sales and service company like Central Carolina Scale for your truck scale needs.

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.