Error 404--Not Found

From RFC 2068 Hypertext Transfer Protocol -- HTTP/1.1:

10.4.5 404 Not Found

The server has not found anything matching the Request-URI. No indication is given of whether the condition is temporary or permanent.

If the server does not wish to make this information available to the client, the status code 403 (Forbidden) can be used instead. The 410 (Gone) status code SHOULD be used if the server knows, through some internally configurable mechanism, that an old resource is permanently unavailable and has no forwarding address.

Error 404--Not Found

Error 404--Not Found

From RFC 2068 Hypertext Transfer Protocol -- HTTP/1.1:

10.4.5 404 Not Found

The server has not found anything matching the Request-URI. No indication is given of whether the condition is temporary or permanent.

If the server does not wish to make this information available to the client, the status code 403 (Forbidden) can be used instead. The 410 (Gone) status code SHOULD be used if the server knows, through some internally configurable mechanism, that an old resource is permanently unavailable and has no forwarding address.

Tech Briefs

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Mayflower's variable engine technology


Mayflower's e3 engine technology uses a pivoted lever arm between the connecting rod and crankshaft. Benefits are said to include major reductions in fuel consumption and emissions.

It is called the Mayflower e3 Variable Motion Engine, and it could bring a new dimension to the efficiency of the internal-combustion engine, say its inventors and developers. Mayflower Corp., a British automotive and specialist engineering and manufacturing company, with operations in the UK, Continental Europe, Asia, and North America, claims that initial test results indicate a fuel-consumption improvement of 40%, with a 50% reduction in emissions. Variable compression ratio and engine "capacity on demand" are other elements of the technology.

The central aspect of Mayflower e3 is described as a pivoted lever arm between the connecting rod and crankshaft. This configuration gives an "elliptical" path to the con-rod big end, which causes the piston to slow momentarily immediately after ignition, allowing the flame to spread faster. It also provides a longer intake and expansion stroke and ensures the piston and con-rod are positioned to provide positive torque. The net effect is to not only improve combustion, thereby increasing power and reducing emissions, but also to create an engine that runs more quietly and efficiently.

Mayflower states that the technology is the result of an 11-year development program and is described as the "brainchild" of Joe Ehrlich. Mayflower has a 33% stake in the technology rights. Giving details of the system in London, the company described the lever arm as being pivoted at a single point attached to the engine housing at one side of the crankshaft. This pivot point can be moved vertically and horizontally to vary the lever arm geometry while the engine is running, which has the effect of enabling variations of both the compression ratio and the capacity of the engine as well as giving the Mayflower e3 the ability to adapt intelligently to load demands. The technology is applicable to two-stroke, four-stroke, gasoline, and diesel engines and is able to complement supercharging, turbocharging, variable-valve timing, and direct-injection technology. Mayflower has invested in a multi-million dollar development program and a commercial realization strategy. According to Mayflower Chief Executive John Simpson, introducing the e3 technology into production engines would "not require (a) huge investment" in new plants and facilities. "Production can be introduced without fundamental change to existing manufacturing facilities," he said. "(The) first engines could be in production within five years."

- Stuart Birch


WABCO offers new ride technology


WABCO's electronically controlled air suspension (ECAS) compensates for unequal load levels from front to back and side to side.

The all-new 2002 GMC Envoy and Oldsmobile Bravada body-on-frame SUVs overcome rear vehicle sagging via WABCO North America's electronically controlled air suspension (ECAS). As WABCO's first North American product application, the ECAS enables a constant ride height, regardless of cargo load. The system compensates for unequal load levels from front to back and side to side.

ECAS is a package of components: compressor, air dryer, electronic control unit, solenoid valves, and bracket. "It's installed as one unit on the frame rail behind the rear wheel," said Chris Sanders, Vice President of New Business Development for WABCO North America in Bloomfield Hills, MI. WABCO's air suspension offering is standard on the Bravada and optional on the Envoy.

"The ride isn't compromised and stays level even when the vehicle is hauling heavy loads or pulling a trailer. Another benefit is that this system keeps the headlights aimed properly, which is important for safety," said Ted Robertson, Chief Engineer for General Motors' Midsize Trucks.

WABCO's two-corner air suspension system employs two height sensors (located on the frame rail in proximity to each rear wheel well) to monitor the distance between frame rail and body. Sensors relay electronic signals to the control unit. As necessary, the onboard compressor module automatically inflates or deflates one or both of the rubber air bladders. Two air bladders replace the coil springs on the five-link rear suspension. "The system changes the internal volume of air in the spring at each wheel," said Sanders.

The system shuts down when overload is detected, marking an industry first for maximum load protection, according to WABCO. When the system is in "jack mode" for a tire change, ECAS will not release air from the springs. "The control and routing of the air is a function of the electronic control unit, which means in 'fail-safe' mode air can be directed to the inflator without depleting it from the springs," said Sanders.

The 2002 Oldsmobile Bravada comes standard with WABCO's ECAS.

ECAS also can be used as a tire inflator via an activation switch and valve located in the right rear cargo area. A stowed 6.7-m (22-ft) airline hose can reach all four wheels. "This is the only compressor that has a tire inflation system," said Sanders, adding that the system—via various included nozzles—also can inflate beach toys, bicycle tires, or sports equipment.

Inflation capability is equal to the volume of one tire being at zero pressure. "The idea, from a safety perspective, is to inflate a tire so you can get to a place where it can be repaired," said Sanders. This inflation feature is not intended as a replacement to the full-size onboard spare tire, which is standard equipment for the Bravada and Envoy.

Early in product development, GM and various subsystem providers shared information. GM and WABCO exchanged CAD data relating to physical dimensional packaging of the ECAS system. "In this example, GM Engineering used virtual product development to obtain answers as to how the suspension performs at the subsystem level—relating to loads and durability—as well as how the suspension affects the ride and handling of the total vehicle," said John Morley, staff project engineer with GM Engineering.

WABCO's ECAS system for trucks and trailers served as the basis for the company's development of the system for cars and light trucks. The system used on the Envoy and Bravada was designed and engineered in France and Germany. The system is manufactured in France.

- Kami Buchholz


Vibracoustic tames ride with balance


This micro-cellular urethane body mount, designed by Vibracoustic North America, is similar to the one used on the 2002 Lincoln Blackwood.

Potholes have little ride impact on the all-new 2002 Lincoln Blackwood truck. Employing hybrid leaf and air springs as well as variable-rate rear shocks with staggered placement, the rear suspension gains added halt-to-axle travel via micro-cellular urethane (MCU) jounce bumpers.

"If the vehicle didn't have MCU jounce bumpers, it would not have as plush a ride," said Neil Cummings, Development Program Manager for Vibracoustic North America, headquartered in Plymouth, MI. "The combination of MCU for both jounce bumpers and body mounts is significant because it brings the ride to a new level and improves NVH." The Blackwood is the first vehicle to employ MCU jounce bumpers and body mounts from Vibracoustic North America.

The conventional material for jounce bumpers and body mounts is butyl rubber. MCU, however, is 20-40% lighter than rubber, and road noise decreases by more than 3 dB compared to rubber. The material has high-volume compressibility, with a lateral expansion of 12% vs. 50% for rubber when under 50% compression.

Rubber's susceptibility when subjected to drastic temperature changes can erode ride and handling consistency. "MCU body mounts and jounce bumpers have 10-20% of the variation of rubber over a given temperature range during vehicle usage, so the vehicle's ride feels more consistent," said Cummings. MCU also is a more linear material over a dynamic range. "When you look at a dynamic vs. a static rate, MCU has a 50% lower dynamic-to-static spring rate ratio than does rubber, which provides the vehicle with a more consistent ride over a range of speeds."

Vibracoustic's micro-cellular urethane jounce bumpers provide more progressive cushioning and offer a softer vehicle ride.

Ford previously has used urethane for suspension bushings. The 2001 Explorer Sport Trac was the first Ford SUV to use MCU body mounts, earning Vibracoustic North America a Ford Significant Truck Achievement Award for the technology.

Vibracoustic engineers conducted FEA, road-tested the Blackwood, and ran spring rate calculations to determine the application's configuration for the MCU body mounts. "We changed the shape of the component (body mounts) from what was on the 2001 Explorer Sport Trac," said Cummings. Because the Blackwood uses the base frame of the Ford F-150 pickup truck, geometry and other alterations were necessary to keep the existing package parameters. "We basically wanted to optimize the spring rate of the upper and lower body mounts while not degrading any of the other ride characteristics or durability."

The 12 MCU body mounts (six upper, six lower) help establish the Blackwood's plush ride while reducing harshness and vehicle shake and attenuating lower drivetrain and road noise. The four MCU jounce bumpers (two in front, two in rear) primarily provide harshness reduction.

- Kami Buchholz


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Error 404--Not Found

Error 404--Not Found

From RFC 2068 Hypertext Transfer Protocol -- HTTP/1.1:

10.4.5 404 Not Found

The server has not found anything matching the Request-URI. No indication is given of whether the condition is temporary or permanent.

If the server does not wish to make this information available to the client, the status code 403 (Forbidden) can be used instead. The 410 (Gone) status code SHOULD be used if the server knows, through some internally configurable mechanism, that an old resource is permanently unavailable and has no forwarding address.