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.

iQUBE acts as a virtual watchman, continually monitoring scale performance. It provides immediate proactive event management to alert operators and technicians of potential inaccuracies or disturbing trends. When an irregularity is detected, the advanced diagnostics will trigger an on-board LED that will change from green to red, indicating which cell is affected. A specific diagnostic message will also display on the 920i when the two are paired together.

With open architecture and advanced connectivity, iQUBE works with existing analog scale systems, new scales, existing indicators and new user interfaces. To make integration easy, iQUBE interfaces using today’s common serial interfaces including RS-232, RS-485, analog, fiber optics and RF wireless. Additionally, on-board Ethernet TCP/IP provides seamless integration from your front office to factory floor. If your business is heavily vested in fieldbus technology, bundle an 820i/920i digital indicator/controller with your iQUBE to easily adapt to DeviceNet™, Profibus® DP, and Allen-Bradley® Remote I/O options.

Inspect load cell cables for damage. If damage is present, the seal is probably degraded as well. To combat this problem, some manufacturers offer rigid or flexible metal conduit to run the cable through, providing a layer of protection that’s nearly impervious to damage from rodents. Even though steel over braid cable provides more protection from damage than cable sheathed with polyurethane or plastic, they still need to be checked as well.

Weather is another enemy of load cell cables. When exposed to moisture, cables can become wicks. Water can be sucked through the cable’s length by capillary action until it enters the load cell or junction box. Once inside, it can damage components and seep into the inner layer of the cable. Wet cables may not cause signal distortion immediately, but they may slowly corrode the copper wires or shield beneath the insulation, causing big trouble sooner or later. Corrosion of the shield limits the cable’s effectiveness in blocking electromagnetic interference (EMI) and radio frequency interference (RFI). Corrosion of individual wires will degrade the signal. If you discover a wet home run cable or load cell, replace it. To help prevent moisture from entering the cell from the cable, bend the cable or flexible conduit downward to create a drip loop at the location just before it enters the cell.

Check the junction box (j-box) for internal condensation, is the most common moisture problem. This occurs from normal air exchanges from heating and cooling cycles, and over-aggressive washing that damages sealing components that haven’t been properly maintained. If left unchecked, wiring terminals and other components in the enclosure will corrode. Due to its material properties, a stainless steel j-box is more vulnerable to internal condensation. If stainless steel is not required, install a j-box with a fiberglass-reinforced polyester (FRP) enclosure. A desiccant bag in the enclosure will help control moisture.

Unlike check rod binding, bumper bolt displacement is easy to spot.  Bumper bolts need to be tight so they don’t move on their own, yet maintain clearance when the scale is both empty and loaded.  Seasonal temperature and weather changes can cause concrete and steel to expand and bumper bolts can bind tight against the contact area.  If binding occurs, adjust bumper bolts to maintain proper amount of clearance for all conditions. Rice Lake SURVIVOR scales do not have bumper bolts.

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.

When deciding how often to have your scale tested, take into consideration your number of weighments, climate and the value of the product being weighed.  Aside from the actual calibration, most of the inspection will consist of you or your scale technician conducting a visual inspection of the scale, foundation and surrounding area.  Every vehicle scale should be calibrated and tested by a state-licensed servicing agent with no less than 25,000 pounds of certified test weights.  A lot of times it is ideal to use a company like Central Carolina Scale in Sanford, North Carolina  that has a scale test cart that can test different areas of the scale.

Pier or Slab Foundation
With an above ground installation, you will have a few foundation options.

Deep Pier
Typical for the northern areas of the United States, the deep pier foundation places part of the foundation below the frost line to eliminate the negative effects that freeze-thaw conditions create with foundations. Similar to the isolated pier foundation, the deep pier foundation also requires 3000 PSF bearing pressure.

Full Slab
A full slab foundation is a continuous or monolithic pour of concrete that runs the entire length of the weighbridge. This is the second most cost-effective type of foundation and is designed for ground that has a soil bearing pressure of at least 1500 PSF.

Pit-type
The pit foundation comes in numerous depths from 2′ to 6′. Your pit depth should best fit your needs and meet all federal, state and local requirements.

Meanwhile the Rice Lake 820i HMI Weight Indicator Controller allows for simplified serviceability and programming support. Any 820i user can automate formula selection, batch start up, data recall and frequently used processes with the push of one button. All of these indicators along with many others are available at Central Carolina Scale out of Sanford North Carolina.  Central Carolina can also calibrate and service the truck scales as well.

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.