Jacobs Vehicle Systems, a worldwide manufacturer of diesel engine retarding systems and valve actuation systems, has introduced its Fulcrum Bridge technology to the off-highway market. The technology is designed to eliminate the need to periodically adjust an engine’s lash settings, reducing inconvenience and total cost of ownership, while making conventional engine braking compatible for the first time with lashless technology, which is widely used by heavy duty engines in off-highway applications.
Jacobs’ Fulcrum Bridge removes the traditional need to set and adjust the mechanical clearance in the valve train between valve and camshaft, known as lash, by employing Hydraulic Lash Adjusters (HLA). Hydraulic lash adjustment allows for more consistent valve motions throughout all engine operating conditions and wear over the engine lifetime, enhancing engine performance and fuel economy.
HLA technology has advantages for engine manufacturers because setting lash on engine assembly lines can cause bottlenecks, and advantages for engine operators as they benefit from a reduction in vehicle downtime because the need to check and adjust lash is eliminated for intake and exhaust main events. This servicing requirement can be especially inconvenient where engines are in use in specialty off-highway applications because a clean environment is needed when accessing the overhead and opening the valve cover, and when getting access to the engine may require significant vehicle disassembly.
Another disadvantage of traditional, manually adjustable lash is that the adjustments are often set with slight inaccuracies, with a detrimental effect on exhaust emissions and fuel consumption. Variance from the optimum setting by as little as 0.01 cm may be enough to negatively affect engine breathing and efficiency, according to the company.
By making conventional engine braking compatible with HLA technology, Jacobs’ Fulcrum Bridge enables all the benefits noted above. Conventional engine brakes were previously incompatible with HLAs because as the engine brake holds the exhaust valve open, the HLA will over-extend, possibly causing valve-to-piston contact once engine braking is turned off. Jacobs’ solution applies a reactive load to the HLA during an engine braking event to prevent this over-extension.
“It was previously thought to be impossible to use Hydraulic Lash Adjustors and engine brakes together, forcing engine makers to choose between HLA’s and a Jake Brake. Jacobs’ Fulcrum Bridge system means you can have both, bringing the many vehicle performance and efficiency advantages of both technologies to off-highway operators. With the Fulcrum Bridge, the lash setting is good for the life of the engine,” said Steve Ernest, vice president of engineering and business development at Jacobs Vehicle Systems.
