The structure and robustness of analogue pressure-type gauges, coupled with the guaranteed availability of spare parts for locomotives in South Africa, outweigh the benefits of electronic instrumentation that has to be sent away for repair or recalibration, says pressure and temperature measurement instrumentation manufacturer and supplier SA Gauge.

Being contracted byState-owned freight utility Transnet to supply its analogue pressure-type gauges for 589 units of locomotive vehicles until February 2018, SA Gauge director Chris du Plessis notes that modern locomotives use electronic instrumentation, but the 6E model locomotives still use mechanical or analogue instruments to measure the pressure or vacuums on the air brake systems.

“The locomotive pressure gauges are of a completely nonstandard specification and all the parts are custom-built by SA Gauge. The parts are not interchangeable with the standard industrial or mining gauges. Once the components are manufactured, they are dedicated for use in a specific locomotive application.”

Du Plessis further explains that the company has manufactured dedicated jigs and fixtures to assist in the distinct nature of locomotive gauges. “Without these raw material profiles and stampings, it would be virtually impossible to produce the gauges with a consistent quality and within the required timeframe.”

He adds that SA Gauge has been producing these gauges since 2005 and also supplies most of the other industrial and mining locomotive manufacturers and reconditioners.

“The speciality of the company is to develop and manufacture to original-equipment manufacturer (OEM) requirements at very short lead times. Special dials and ranges can typically be done within two days. Customer logos are also designed and printed in-house, ensuring quick turnaround times,” he points out.

SA Gauge’s pressure and temperature gauge manufacturing standards follow the guidelines set by the EN 837-1 standards.

The SA Gauge Pressure Calibration Laboratory is Sanas ISO/IEC 17025:2005-accredited.

The company uses computerised machining centres and presses to manufacture the components needed to assemble the pressure gauges in locomotives.

“Many of these machines can produce high-accuracy components with minimal supervision, enabling the company to cope with large orders just as easily as it can cope with small specialist orders,” says Du Plessis.

“SA Gauge currently employs 48 people, six of whom are technically qualified in the manufacturing division, with two metrology certification scheme-certified metrologists working at the company’s calibration laboratory and two graphic designers ensuring that in-house dial design and other special OEM requirements are speedily met. “All Sanas-accredited calibration laboratories are required to have such a person to sign off calibration certificates,” he concludes.