A new way of driving an off-road vehicle * MONROE ADVENTURE * Freedom, safety and comfort

INTRODUCTION Brussels (ots/PROTEXT) - Thirteen years after the launch ofthe Monroe Gas-Magnum 4x4Ž shock absorbers, Tenneco Automotive -a world leading manufacturer of ride control systems - introducesa range of innovative shock absorbers for off-road vehicles, theMonroe Adventure, designed to meet the needs of a rapidlygrowing off road car park.In studies of the off-road market, Monroe found out that only 10%of these vehicles are driven off road, while the majority (90%)are actually driven on road. Suspension therefore, originallydesigned with a high rigidity in off road vehicles for absorbingthe impact of rough terrain, would have to provide increasedcomfort for on road driving.In designing its new 4x4 shock absorber, Monroe has tried to findinnovative solutions to combine safety and comfort both on andoff road into a single all-purpose shock absorber. The result isthe new Monroe Adventure, a monotube shock absorber whichensures the driver's safety and comfort on different roadsurfaces and various driving conditions, and whose highperformance remains unaltered throughout its entire life.TECHNOLOGYBut why choose a monotube shock absorber? The monotube designexposes the shock body to maximum airflow, lowering the operatingtemperature of the internal components and fluid, therebyextending the life of the shock absorber. In addition, thisparticular design allows for a corresponding larger piston (46 mmin diameter instead of the 34.9 mm of a twin-tube shock)therefore allowing higher sensitivity to wheel motions.Inside the shock absorber, the nitrogen gas (which unlike air,does not change temperature when compressed) is separated fromthe superior grade oil by a specially designed, close tolerance,floating piston. This provides a constant pressure of 360 psi (20bars) against the hydraulic fluid, absolutely eliminating anycontact between gas and oil and the performance loss that iscommon to conventional twin-tube shocks, as the emulsion provokedby overheating creates micro-cavities (the emulsion/cavitationphenomenon) which prevent the smooth operation of valves.The total elimination of foaming results in uninterrupted dampingfor even the smallest wheel deflections (2 mm): performance whichno other type of shock can match.SPECIFICATIONSThe self-adjusting working piston (46 mm in diameter), withspring-steel valving discs, precisely regulates oil flow foroptimum compression and rebound control. There are no checkvalves or springs to wear out.A high-viscosity superior grade oil guarantees uninterrupted andoptimal damping at different temperatures ranging from -40°C to+120°C. When driving an off-road vehicle in particularly dryareas, the shocks temperature can even reach 100°C.The piston rod, with a diameter of 14 mm (unlike the conventionalmodels currently available on the market, which have a diameterof 11 mm) is hard-chromed uniformly without intermediate layers,and is the strongest in the industry. The self-lubricating rodguide and end seal insures longevity and prevents leakage, aswell as corrosion and dust penetration.The tube wall has a thickness of 2 mm (against the 1.27 mm ofconventional twin-tube models), therefore the damage provoked bystones or external blows is drastically reduced.These unique design features function in unison to allow MonroeAdventure shocks to operate at peak performance levels for life.ADVANTAGESThe Monroe Adventure shock absorbers ensure five innovativeadvantages:Better heat dissipationA shock is an energy converter. Spring energy has to be convertedinto thermal energy and the resulting heat has to be dissipatedas quickly as possible.A shock absorber's effectiveness is directly proportional to itsability to dissipate heat, since a 'hot' shock quickly loses itsdamping ability.In conventional twin-tube shocks, the heat must pass through twotubes. New Monroe Adventure monotube design results in a coolerrunning, more efficient and durable shock.Innovative piston designThe greater piston area - as a result, among other things, of thelarger space available in monotube shocks - provides greatersensitivity for small piston movements to achieve effectivedamping at wheel motions as small as 2mm.Lighter weightThe reduced 'unsprung mass' allows wheels and tyres to respondmore readily to surface irregularities for improved control.Additionally, by reducing the unsprung mass, wear and tear onsuspension and steering components is reduced.High-pressure gasThe permanent pressure exerted on the oil by the gas ensuresinstantaneous response as well as a smoother operation of pistonvalves. In addition, the gas pressure eliminates cavitation andfoaming phenomena which could compromise the shock function, inparticular under severe driving conditions.More safetyAll these characteristics ensure safer driving conditions both onroad and off road, as well as higher comfort.'The tyre to road contact is increased under any drivingcondition, both on road and off road' says Jean-Pierre Dolait,Vice President of Tenneco Automotive Europe's Aftermarket Salesand Marketing division. 'In the case of an emergency stop, thebraking distance is strongly reduced. A safer journey is alsoguaranteed under diverse weather conditions such as rain, wind,snow and ice. The new Monroe Adventure shocks - concludes Dolait- indeed allow for better vehicle control on the road as well asin extreme situations.''The new shock absorbers designed for off-road use - underlineTenneco engineers - protect all the fundamental components of thevehicle, tyres included, against early and hazardous wearing.'WORKING PRINCIPLEMonroe Adventure does not need manual adjustment to compensatefor wear or for varying road surfaces. The shock respondsinstantaneously to the speed of suspension movement to providethe exact damping characteristics required for maximum control,safety and performance. But, how has been possible to achieve allthis?A piston fixed to the car body by the piston rod slides into oilfilled cylinder that moves together with the wheel. During thatmovement calibrated openings in the piston allow the oil to passbetween the upper and lower chamber of the cylinder, so dampingthe oscillation of the spring. The monotube shock absorbercontains at one end a small quantity of an inert gas (nitrogen)under high pressure (20 to 25 bars). A floating piston separatesthis gas from the oil.During the compression stroke, the rod changes the volumeavailable for the oil, which compresses the nitrogen. During therebound stroke, the rod moves out again, and the gas pushes thefloating piston back to its original place.The force generated by the damper during its rebound orcompression stroke must be variable in function of the vehiclespeed and of the road surface. The reaction forces must be ableto control the car body movements on motorway at high speed aswell as the fast movement on a bad road at low speed and stillproviding the best compromise between comfort and road holding.THE VALVINGThe Monroe Adventure shocks have 3 stage valves to provide theideal damping under all circumstances. The first stagecorresponds to the low piston speeds (motorways), the 2nd stageto the medium speeds (standard or dirt roads) and the 3rd stageto the high speeds (off-road tracks).The monotube valving functions as follows:1st stage (low piston speed): When for instance the shockabsorber is slowly extended, the piston and the rod move upwardsand force oil to flow from the upper chamber to the lower chamberthrough the piston valve. It flows successively through the holesin the piston and through the constant orifices (bleeds) shapedin the discs at the bottom of the piston. Due to the very smallsize of the bleeds, the flow resistance of the oil increasesrapidly with the piston speed.2nd stage (medium piston speed): When the piston speed increases,the pressure is high enough to lift the discs The dampingcharacteristic is now linear.3rd stage (high piston speed): When the piston moves very quicklyinto the cylinder, it is necessary for the damping force toincrease rapidly as well to prevent topping. So, at that momentthe discs are completely open and their limited opening now forma restriction that builds up a higher resistance for the oilflow.The permanent pressure exerted on the oil by the gas guaranteesan instantaneous response as well as quieter operation of thepiston valves.COVERAGEMonroe has always invested a large part of its resources inoffering the best coverage in the industry.Hard work of research, market analysis and new vehiclesidentification are the key for Monroe to offer 96% coverage for4x4 vehicles.REPLACEMENTGenerally speaking, shock substitution frequency depends on theuse of the vehicle and the conditions of the road surface. Onaverage, shock absorbers should be replaced every 50,000 kms, andchecked every 20,000 kms. Drivers are recommended to replace allthe shocks fitted on the same axle at the same time, similarly tobrake disks and tyres, because for increased safety, the shockabsorbers on the same axle must ensure identical performance.Tenneco Automotive headquartered in Lake Forest, USA is theworld's largest producer of ride control and emission controlproducts under the MonroeŽ and WalkerŽ brand names. With 23,000employees and a turnover of USD 3.5 billion, the company has over100 facilities in 22 countries in North and South America,Europe, Africa, Australia and the Far East.For Additional Information:Simonetta EspositoCommunications ManagerTenneco Automotive EuropeTel: (00)322-706-9147Fax: (00)322-706-9199Email: Simonetta.Esposito@eu.Tenneco-Automotive.com

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