Air springs control ride-height and load compensation on most heavy trucks today. An engine-driven air compressor maintains constant line pressure. As the distance between the axle and the frame decreases to less than a permissible minimum, a mechanical linkage actuates the air-leveling valve that admits air into the bladder. The same valve exhausts air when the distance between the frame and axle becomes excessive.
With no reservoirs to leak and no poppets to jam, the compact valve is unaffected by normal contamination. Of rotary design and containing only one moving part, the valve relies on lapped surfaces to affect a seal. Compressed air does not flow across sealing surfaces, but directly through the inside diameter of the seal. The relative movement of two circular, overlapping ports affects valve operation to ramp the flow rate and eliminate full-on/full-off behavior.
A 1.58 deadband prevents nuisance valve actuation during normal suspension travel. Exhaust and fill times are 11/2 to 21/2 times quicker than those of other systems. And an integral fast-flow dump port permits 10-sec system depressurization prior to driving away from parked trailers.
Mechanical link between truck’s axle and frame-mounted air-leveling valve helps maintain the pre-set ride-height pressure in the air
Air, together with any contaminants, flows into the leveling valve through the center of its pressure seal and does not flow across sealing surfaces.
Submit your ideas and rough drawings for this section to John Lewis, Designer's Corner, Design News, 275 Washington St., Newton, MA 02458
Paul O'Reilly Barksdale Inc. 3211 Fruitland Ave. Los Angeles, CA 90058 (800) 835-1060
Some humanoid walking robots are also good at running, balancing, and coordinated movements in group settings. Several of our sports robots have won regional or worldwide acclaim in the RoboCup soccer World Cup, or FIRST Robotics competitions. Others include the world's first hockey-playing robot and a trash-talking Scrabble player.
A recent example of a major CAE revamp is MSC Apex, released last month by MSC Software Corp. In a discussion with Design News, MSC executives noted that its next-generation platform is designed to substantially reduce CAE modeling and process time, “in some cases from weeks down to hours.”
The Thames Deckway would run for eight miles close to the river’s edge, rising and falling slightly with the tidal cycle. It will generate its own energy from a series of devices that will line the pathway and use a combination of sources to make the path self-sustaining.
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.