Over the last 35 years, Thames Side has specifically developed a range of load cells and instrumentation/electronics for accurate, commercial (trade) weighing of vehicles driving onto truck scales/weighbridges.
A truck scale, or weighbridge, is essentially a large platform scale that is used to weigh an entire vehicle, for the purposes of reading the weight of the vehicle before it is filled with material, or after it is emptied. Often a truck scale is a legal-for-trade approved scale used to issue tickets that will be used for commercial (invoicing) purposes. Commercial truck scales must be calibrated by a certified company, using verified and traceable measuring equipment. Therefore truck scale load cells usually need to be approved according to an organisation such as OIML or NTEP.
For permanent or semi-permanent truck scales/weighbridges the weight readings are usually recorded with equipment located in a nearby hut or office. Most weighbridges are now linked to a PC that runs truck scale software – this controls barriers, traffic lights, RFID card readers, enables theprinting of tickets and provides reporting features.
There are various different types of truck scale around the world, with each region tending to favour a particular type. The most common 3 types have from 4-16 load cells and of maximum length 18 or 36 metres, as follows:
- Traditional Fabricated Steel; high or low profile design
- Pre Stressed, Pre Cast Concrete; low profile design; modular
- Poured on Site Concrete; single span or modular steel frame with concrete infill
Our Solution: T34 Compression Rocker Column Load Cell
Thames Side Sensors is a market leader in the design and manufacture of industrial truck scale/weighbridge load cells, which were specifically designed for such applications. Thames Side’s trusted and dependable model T34 compression rocker column load cell is the ideal solution for truck scale installations and more than 300,000 units of this design have been installed worldwide in a variety of different environments – a figure that shows universal acceptance by the international truck scale/weighbridge marketplace.
Typical problems encountered with truck scale/weighbridges:
- Pit mounted truck scales/weighbridges can be affected by rain, flooding, dirt and rodents etc. Installation of a truck scale/weighbridge near lowered areas of road or ground should be avoided – this prevents rainwater or floodwater running down into the pit area, which would cause the load cells to be submerged.
- Additionally, as for all multi-cell platform scales a truck scale/weighbridge system must output the same value no matter where the weight is positioned on the scale. For example, if atruck carrying liquid drives onto the scale and stops suddenly, the centre of gravity of the truck will be moving around for some time. Waiting for the centre of gravity to stabilise is not an option; productivity would be seriously degraded in such circumstances. If the sensitivity values of the load cells were all significantly different, the weight reading would change depending on where the centre of gravity of the truck was located. The solution: choose load cells that have been pre-corner adjustment optimised during their manufacture and calibrated in mV/V/Ohm to provide matched current outputs. This allows for much faster commissioning of the truck scale/weighbridge because minimal (or no) corner adjustment is required. Thames Side’s Model T34 compression rocker column load cell is pre-corner adjustment optimised @ ±0.05% by calibration in mV/V/Ohm.
Digital Load Cells
An even better solution is to use digital load cells. The Model T34D digital compression rocker column load cell provides the following advantages and benefits over the standard (analogue) T34 load cell:
- Higher resolution (up to 1,000,000 steps from zero to full scale) – resuting in a more precise truck scale
- Intelligent, error-free compensation for each individual load cell, with simpler and faster corner adjustment – which saves time during troubleshooting
- Simpler and faster maintenance with continuous, individual self-diagnosis
- Remote diagnostics via modem using direct PC connection (with the Matrix 2 weight controller) – therefore the site does not have to be visited to determine if there is a load cell fault
- Greater EMC protection against interference (digital signal transmission) – meaning less signal error
- Direct PC connection via RS485 bus and RS232 converter, up to 1200 metres away – meaning that the control room does not need to be close to the truck scale
- Internal signal filtering for each load cell, resulting in a more stable output
Many of our local weighing system Partners, who are experts in their field, will be able to supplytruck scale calibration services if you wish to have your system calibrated or certified.