Specialist Mechanical Engineers

Custom HVAC and Filtration Systems for the Rail Industry

907 Hertzog Street,
0084 Pretoria,
South Africa

Specialist Mechanical Engineers (SME) is a South African company, specialising in custom industrial, rail and military heat transfer, ventilation, air conditioning (HVAC) and filtration systems for use in adverse environmental conditions.

SME prides itself on having supplied products for over two decades, including more than 1,500 qualified coach and loco systems in numerous designs for a wide variety of applications within the railway industry.

Designs include stand-alone modular roof mount, front-panel mount, ruggedised split and under-sling environmental control systems (ECS) for drivers, sitter and sleeper cabins, cooling of equipment, walk-in freezers, under-counter fridges and high capacity / fast freezers.

These custom train HVAC systems can be found in locomotives and coaches, including 6E/18E, 7E, 9E, 11E, diesel 34 loco, diesel 39 loco, metro 10M5, ShoshalozaMeyl, Blue Train and PelaPepa.

Locomotive cabin air conditioners

Units are generally of modular design for service exchange within 30 minutes and can be front-panel mount or packaged roof units. Where required, split designs are integrated with either under-sling condensing units or installed in the motor room behind the cabin. Cabin evaporators of split units can be wall or floor-mounted modules or custom integrated in the driver’s console.

Coach / saloon HVAC systems

For saloon ventilation and air conditioning, multiple modular or split units can be offered or single roof mounted to suit specific car designs. The latest technology high-efficiency scroll compressors are used in tandem for redundancy, as well as effective capacity control in accordance with the load. Heating can be supplied by evaporator integrated elements, separate heating or reverse cycle heat pump design.

Special fresh air filtration modules can be added for heavy-duty and dusty environments, where self-cleaning cyclone cartridges ensure at least 95% clean air to occupants. CO2 sensors add to energy-efficient designs for dense metro applications to adjust volume flow and cooling capacity to actual levels required.

Extreme temperature reliability

All units for rolling stock are developed to operate reliably under extreme temperatures, humidity, shock and vibration, and dusty environments. To live up to this standard, all units are performance tested in our climate-control room, as well as being vibration and EMC tested where necessary to ensure optimum performance and compliance with the relevant specifications and procedures.

Efficient power management and communication interface

Intelligent control allows for efficient power management and communication interface options, such as CANbus or custom protocol to the train central management system. Bluetooth and USB links enable download of system history and error logging to reduce fault finding time and potential downtime. The units are also well protected against extreme supply power and phase variations.

Product support and spare parts

SME offers comprehensive product support with detailed documentation and reliable spare part availability for up to 15 years if required. In South Africa we have established our own dedicated support facilities in Pretoria, Johannesburg, Cape Town, East Londen, Durban, Richardsbay, Kimberley, Nelspruit and New Castle.

SME strives to deliver HVAC products which are:

  • Environmentally friendly
  • Compact and quiet
  • Have a low lifecycle cost
  • Maintenance friendly
  • Suitable for very harsh conditions

Ruggedised Split HVAC

The 7.5kW Split System with reverse cycle function is a ruggedised split heating, ventilation and air-conditioning (HVAC) system.

Coach Rooftop HVAC

Roof-mounted modular heating ventilation and air-conditioning (HVAC) system to supply 20kW cooling and 9kW of heating, to ensure a cabin temperature of 20°C-25°C max in a 45°C ambient, provided the coach is thermally insulated.

CAB HVAC Rooftop Unit

Rooftop-mounted modular air conditioning system (ACU) to supply 8kW cooling to ensure a cabin temperature of 20°C-25°C max in a 55°C ambient, provided the cabin is thermally insulated.

MAC Smart Control

The SME multi-application control (smartMAC) system is designed for innovative in-house engineering, including the development of advanced electronic controllers for all our heating, ventilation and air-conditioning (HVAC) units, as well as auxiliary power units (APUs).


Mounted to the side of a diesel locomotive, our air-conditioning system (ACU) supplies 8kW cooling to ensure a cabin temperature of 22°C-25°C max in a 45°C ambient with thermal insulation.

Specialist Mechanical Engineers (Pty) Ltd (SME)

907 Hertzog Street




South Africa