Imperial Engineering offers advice on the importance of oil changes in hybrid compressor maintenance
Entering the UK market around five years ago, hybrid buses such as the Volvo B5L and LF are now commonplace in operator fleets delivering urban services with stringent environmental controls, such as Transport for London’s ULEZ, which operates 24 hours a day, seven days a week.
Hybrid vs. diesel
Although visually similar to a conventional diesel bus from the exterior, hybrid buses are fundamentally different inside when it comes to producing the compressed air needed to provide the main energy source for the air braking, pneumatic suspension and door opening systems.
While diesel-powered buses use engine-driven air compressors, hybrids typically feature standalone electrically driven screw compressors from OEMs, including Knorr-Bremse and Gardner Denver, to supply constant and stable compressed air.
Unlike diesel driven compressors that are lubricated and cooled by the engine’s oil circuit, electric hybrid compressors feature an independent lubrication system.
As a result, these systems require regular oil and filter changes in line with the compressor manufacturer’s recommendations and a vehicle’s duty cycle to ensure the intended service life of the system.
Conventional compressors require minimal maintenance, are designed to provide an average service life of five years and cost around £500 to replace (depending on the make and model of the vehicle).
By comparison, standalone electrically driven compressors can cost up to 10 times more than their diesel-driven counterparts to replace.
As a result, maximising the service life of electric compressors has become a key consideration for operators seeking to run their hybrid fleets as efficiently as possible. Research undertaken by Imperial Engineering (IE) recommends that operators increase the inspection and service of electric compressors on a regular basis, in line with the OE manufacturer recommendations and local duty cycles.
By increasing hybrid compressor maintenance, including regular oil and filter changes, operators can increase service life, reducing the overall operating cost of the compressor.
To help make the servicing of hybrid compressors easier and more cost-effective for operators, IE has recently introduced a range of service kits. These feature Knorr-Bremse OE filters and the correct grade of synthetic Volvo B5 Hybrid Compressor Oil, which is available in one or 20 litre containers.
IE has a wealth of compressor system knowledge and is pleased to support operators with technical advice and guidance.
For further information call 01992 634255 or email [email protected]