Powertrain Systems

Delphi's Hydraulic Lash Adjusters are used in internal combustion engines with overhead-cam valve train systems. They support the pivot ends of rocker arms while automatically controlling the rocker arm positions to keep them in contact with the camshafts and valves. The range of the hydraulic lash adjuster accommodates engine build tolerances so no adjustment is required during engine assembly and also compensates for variation that occurs during the life of the engine so no service is required. They also provide lubricating oil for overhead components such as the cam⁄rocker arm interface and the rocker arm⁄valve tip interface.

Delphi's 12 mm Hydraulic Lash Adjusters are designed to provide these capabilities in a very small, lightweight package. Emphasis in development was building quality into the design as well as maximizing durability, maximizing hydraulic stiffness for best valve train dynamics, and minimizing cold start noise.

Benefits

• No adjustment required at engine assembly
• No adjustment required in service (the only service requirement is normal oil changes)
• Overhead oil lubrication to the rocker arm interfaces helps provide improved engine durability
  

Typical Applications

Delphi Hydraulic Lash Adjusters are engineered to meet the needs of end pivot rocker arm valve train systems where small packaging space is required as is typical of dual overhead cam valve trains. They can be used in gasoline, diesel, and alternative fuel applications. Two 12 mm diameter (Ø) designs are available:

• 3.95 mm radius spherical end with a 35.6 mm minimum extended length
• 4.2 mm radius spherical end with a 33.2 mm minimum extended length
• This hydraulic lash adjuster features a higher alloy plunger material for better wear resistance in diesel applications

Specifications Diagram

This illustration shows outside dimensions for installation of the Delphi Hydraulic Lash Adjuster. All specifications are shown in millimeters.

Performance Advantages

• High hydraulic stiffness enables engines to achieve better dynamic control at high speeds (7,000 rpm)
• Large oil reservoir and oil flow capability is optimized for minimal potential cold start noise
• Hardened steel plunger and body provides life-of-engine durability
• Optimized for shipping and engine assembly
• Shipped with a lower viscosity oil in the high pressure chamber and motor oil in the oil reservoir
• This enables the Hydraulic Lash Adjuster to adjust more quickly during engine assembly and prevents valve-to-piston interference and valve spring coil bind
• Chrome alloy ball check valve reduces potential sticking and effects of contamination
• Small size requires minimal space and has less mass than larger designs

Delphi relies on its global capabilities, consistent processes and extensive testing to develop and manufacture valve lifters. The result is that Delphi provides customers with robust, reliable systems and world-class quality.

 The Delphi Advantage

Delphi has more than 75 years' experience in valve train systems and our high-quality conventional valve train products have earned industry-wide respect.  Our deep understanding of the combustion process and our vast research and development capabilities have also enabled continuing innovation.  Delphi is also an industry leader in engine management systems, so whether a customer chooses a complete system or an individual component, Delphi's systems expertise is built into every product and we can help manufacturers achieve higher levels of performance and regulatory compliance.