Mettler Toledo Truck Scale Weighing Components

CWIS offers a complete range of METTLER TOLEDO weighing components for Truck Scale vehicle weighing application ranging from Analogue system, Digital System and to the Most Advance Fully Digital system POWERCELL®.

Weighing Components of a Truck Scale system

Load Cell – Analogue, Digital and POWERCELL® Technology
Junction Boxes if applicable
Weighing Terminal
External Display

Load cells are the heart of any truck scale. They are the sensors that measures the weight of objects on the scale deck. Most truck scales require 6-12 load cells. They must work together flawlessly to provide accurate weight readings.

Analog Load Cell
A precision-shaped piece of metal, often steel or stainless steel, that changes its shape slightly as a force (weight) is applied. The change is monitored by electrical strain gauges. The result is an analog voltage signal that varies from the input signal based on the load. The analog signals from all of the cells are summed in one or more junction boxes at the scale. The combined signal is then transmitted to the scale house, where it is measured and converted to a digital signal that indicates the weight.

Pros	Cons
Low Cost	Limited accuracy
Well-known technology – most scale companies offer an analog load cell option	Typical load cell life is 3 – 5 years
	Requires junction boxes which are a common source of problems
	Require time-consuming manual adjustment for calibrations
	Cannot check the status of individual load cell signals in the system

Digital Load Cell
This is a load cell that generates an analog voltage, which is converted into a digital signal within the load cell enclosure. The data from the cells is processed to determine the total weight. Utilizing a digital signal at the load cell and beyond provides advantages because the signal is not susceptible to interference like analog load cell signals.

Pros	Cons
Signal is less prone to interference and weighing errors	Higher purchase price than analog system
Can offer diagnostics features	Not offered by all suppliers
	Proprietary protocols

POWERCELL® Load Cell
These load cells utilize digital electronics and are equipped with signal- processing capabilities at each load cell. The load cell can eliminate errors by monitoring and adjusting the weight measurement based on a number of criteria. This process is called digital compensation. POWERCELL load cells have also introduced features, such as predictive diagnostics, self-monitoring, breach detection and remote diagnostics.

Pros	Cons
POWERCELL® Load cell	High initial cost
Strong signal - less prone to interference and weighing errors	Proprietary protocols
Built-in diagnostics features
Digital compensation
Self-monitoring
Simplified service and remote access
Breach Detection
Cables and Connection – Detachable cables with stainless steel braided sheathing to protect from physical damage
StrikeShield™ Lightning Protection
No Junction Boxes

Junction Boxes

Junction boxes are used with analog load cells, as well as some digital load cells. Junction boxes combine the signals of multiple load cells and then transmit the summed signal. Inside each junction box are manual wire connections that are made when the scale is installed, along with a circuit board that combines the signals and potentiometers for making manual adjustments. A typical truck scale using analog load cells will have 2 to 4 junction boxes.

Junction boxes are the leading cause of scale malfunctions and service calls. Typically, it is the result of moisture reaching the electronic components and manual wire connections within the box. Moisture causes corrosion and damages circuit boards.

Weighing Terminal

Your scale will have a control unit, often called a terminal or indicator. They can range from simple to elaborate. Below are some of the advanced features you may consider when choosing a terminal:

Control more than one scale with a single terminal
Connect with USB/Ethernet to computers and networks used to interact with scale software, transfer data across company networks and use remote diagnostics

Connect wireless connectivity with the scale and other accessories
Automate other scale accessories, such as gates and lights for traffic control
View data on graphic displays with varying levels of detail
Store tare/net weights with various memory capacities for transaction logging
Connect to various compatible ticket printers

The terminal also may serve as the power supply to some or all of the load cells. Some will specify how many load cells they are able to support. If the supply power to the terminal is subject to fluctuation in your area, consider using an aftermarket power conditioner.

Remote Display

A remote display is a numerical display unit that indicates the weight on the scale. They are often placed at the front of the scale so the drivers and/or filling operators can see the weight of their truck when it is on the scale. Weights are easy to read at distances up to 30 meters. The LED display shows up to six characters, plus designators for weight units (pounds, kilograms or other units) and gross/net weighing.

POWERCELL® Achievements

POWERCELL load cells have been at the forefront of development and achievements in heavy-capacity weighing technology. Since the 1980s, the POWERCELL line has been a breakthrough technology and has been awarded many United States and international patents, including:

First to convert analog signals to digital within the load cell (US Patent 4’815’547)
First to perform digital compensation inside hermetically sealed load cells (US Patent 4’804’052)
First to compensate for hysteresis (loading history) (US Patent 5’308’931)
First to compensate for creep (loading duration) (US Patent 4’691’290)
First to eliminate junction boxes (US Patent Pending)
First anti-rotation feature on column compression load cells (US Patent 4’955’441)
First load cells equipped with an enclosure breach detection system (US Patent 8’055’456)
First to use predictive diagnostics (US Patent 6’576’849)