Portal Gear Lift
 | It has been suggested that this article be merged into Portal axle. (Discuss) Proposed since February 2019. |
The portal gear lift is a device installed onto automobiles, utility task vehicles (UTVs), all-terrain vehicles (ATVs), farm equipment, and military vehicles that need to withstand rough conditions but still maintain power.[1] The power created by the vehicles engine that would normally be transferred directly to the wheel by the drive shaft and axles only, is capable of producing a certain amount of torque based on its current gear configuration. The design of the portal gear box allows for additional gear reduction to be placed near each wheel hub thus generating more torque and creating less stress on other driveline components.[2] This allows for larger tires to be added to vehicles, while still conserving torque. The kit also lifts the vehicle and provides heightened ground clearance by lifting the entire axle system.[3] Most axle systems run straight into the wheel, this is efficient for traditional vehicle use, but if a vehicle needs to withstand rough environments, this is impractical.[4] The portal box allows for stress to be taken off the drivetrain components, which in turn helps vehicles maneuver and avoid damage through rough conditions.
The traditional design includes an input and output shaft attaching to the hub and the axle, both a spur and helical gear train unit, bearing, and casing.[4] The portal axle sits above the center of the wheel hub, with the gears connecting these. The small gears in the portal box are directly rotated by the axle, while the larger gears are rotated by the smaller gears.[4] This transfers the energy off of the axle and onto the wheel.
The method behind gear reduction in all-terrain vehicles is comparable to the gear reduction necessary in ten speeds. If a ten-speed bike is traveling up an incline, it is essential the driver downshifts or they will not make it up the hill. In off-roading vehicles with the portal box, they are essentially downshifting when going through rough terrain.[3] This allows the vehicle to push through rough terrain while still maintaining optimal speed and torque.
Origin[edit]
Portal Gear Lifts have been around for many years. The design was first used in the German military but has since expanded to use in agriculture, racing, and recreational vehicles.[5] Portal use in off-road recreation vehicles like utility task vehicles (UTVs) and Jeeps is becoming increasingly popular today.[6]
Automobile Background[edit]
Portal boxes were first used on automobiles in WWII.[5] The Volkswagen Type 82 Kübelwagen, designed and created by Ferdinand Porsche,[5] was used by the German military for light work. The intent behind this vehicle was to create a car that could drive slow enough to match the tempo of the marching soldiers while still being reliable for off-roading.[5] The design included portal gear hub reduction technology. This technology was used to give lift and gear reduction to military vehicles. There is a long history of this technology being used in automobiles and in recent years the technology was applied to off-roading vehicles. The portal box design increased vehicle capability by giving them more clearance and a lower gear ratio to achieve higher torque[3] — qualities that are especially advantageous in off-road applications where clearance and terrain quality can't be guaranteed.
The history of the technology used in the portal gear lift starts in the automobile industry. Mercedes Benz is known to be one of the companies that mastered the use and application of this technology early in automobile history. First produced in 1955,[7] the Unimog was one of the first trucks built to withstand bumpy terrain. They are still today known as one of the most reliable vehicles in off-roading. The many principles used in creating such a stable vehicle became known as the Unimog Principle. This principle included gear reduction technology.[7]
Mopar portal boxes are a similar technology which have been used in Jeeps to provide sturdy off-roading. Jeeps are known to be one of the most popular all-terrain vehicles today. The use of portal box technology provides clearance and gear reduction in a simpler, bolt-on style kit.[6]
UTV/ ATV Portal Use History[edit]
Utility task vehicles (UTVs) and all-terrain vehicles (ATVs) have grown in popularity since the 2000s. With Polaris, Can-Am and, Yamaha leading the market in sales.[8] The increase in vehicle popularity has also led to substantial technological advancements in the industry. One of these advancements, Portal gear boxes, are aftermarket additions used to lift the vehicle and increase torque and power for off-roading purposes. The portal gear lift also became necessary to relieve stress on drive shafts and axles from the extra weight riders were adding due to bigger tires and other upgrades to their machines.[2] Major advancements have occurred in UTV portal gear lift technology since their invention.
The first prototypes made by leaders in the ATV/ UTV industry were bulky and chain driven. Making them incredibly loud, heavy, and impractical.[2] After more prototypes were created, they became lighter, dropped the chains, and became more efficient. After the first time hitting the market, engineers in the industry made refinements and released a second generation.[2] Today the design used is lighter, stronger, and more efficient than ever.
Design Features [edit]
The design of the portal gear lift is a fairly simple design that causes a big impact on driving quality. The portal box has both small and large gears inside.[3] The small gears are rotated by the axle itself and then they rotate the larger gears.[4] This gear interaction is what allows for the increased torque. The portal box is attached to hub centers and the axle. This attachment allows the entire tire to rotate as the gears do. The portal gear lift is made up of an input shaft and output shaft that attach the axle to the system and are designed to withstand the stress that the axle cannot.[4] Energy is transferred first from the engine to the drive shaft, then to the axle, then to the portal box and finally to the wheel. This chain of transferring energy is important in taking pressure off of the drivetrain. Choosing the right material for the casing of the box is also important, it shouldn't be too heavy or too light. Finding the precise balance of weight and strength when designing the portal gear lift is essential to its effectiveness.[4]
Usages[edit]
Today the portal gear lift is used to upgrade many vehicles for different purposes. Farming, military, leisure, and off-road vehicles are all using portal boxes to add lift, and performance. These benefits allow vehicles to perform in the toughest of conditions including war zones and rural farmlands.[1] All-terrain vehicles and utility task vehicles are the most recent type of vehicle to use of the portal gear lift because these vehicles are often used in a leisure, military, and farm setting. UTVs often fit into military helicopters, can be dropped from above, and give soldiers a better source of transportation than on foot, making them an optimal choice. Adding portal gear lifts to military vehicles adds more ground clearance and torque to the machine.[1]
Farmers use machines with the portal gear lifts because they help with reliable travel through rough farmland. Leisure ATV and UTV riders are a big market for portal gear lifts because they add style and performance. Portal gear lifts allow for bigger more prominent tires and are highly sought after in the riding community. Adding lift and torque allows recreational drivers to travel on intense trails and ride through deep mud without damaging the vehicle.[1] The portal gear lift can contribute increased performance to many different vehicles and assist drivers.
Performance Gains[edit]
Adding larger tires to a vehicle lowers its speed and power by adding weight and tire circumference. It takes a machine more torque and time to rotate bigger wheels.[3] The combination of big tires and adequate torque is highly sought after by both professional and leisure drivers. Not only are big tires a popular style they also allow riders to take on more demanding courses. Portal gear lift kits allow riders to add bigger tires to their machines and still maintain speed, power, and performance.[1] The most common desired benefit of the portal gear lift is the increased torque and ground clearance but there are many more benefits to utilizing portals. The increased torque is achieved through gear reduction which also reduces stress on the axles and drivetrain.[1] Axles and suspension maintain their factory geometry because the lift is achieved in the hub itself rather than in the shocks or suspension.[3]
Ground clearance is increased in two ways when adding the portal gear lift to a vehicle. By adding the lift, it allows for bigger tires to be added, which increases the clearance substantially. The lift is also increased four to eight inches depending on the size of the portal added.[1] The larger tire and the portal height combined to provide the optimum lift and ground clearance for off-roading.
Gear reductions tend to lower maximum speed and increase torque. They are usually used to offset the extra mass and diameter of larger tires which reduce torque. Many ATVs and UTVs have continuously variable transmissions (CVT), which adjust continuously while accelerating.[3] This transmission may operate differently but it still has gears that affect the torque of the machine. Factory gear ratios are determined based on factory spec equipment. When new equipment is added and specs change, gear ratios may no longer be adequate to run the machine with the same amount of torque.[1] The bigger the tire circumference the less torque the vehicle will have, and the more necessary gear reduction is. If both a small tire and a large tire were rolled next to each other, the bigger tire would go farther in one revolution. But, if you install a small tire and big tire onto a machine, the bigger tire would need more power to turn, which reduces torque in a vehicle.[3] Gear reduction can replace this lost power. The gear lift multiplies the amount of torque at the wheel and puts less stress on the drivetrain. So that overall the torque can be conserved, and the machine will gain stability, speed, and power.
When ground clearance is enhanced, brakes become more protected from dirt and debris. The extra lift the portal provides also provides extra protection.[1] With less debris and dirt interfering with the brakes, they will perform better and last longer. Studies have shown that brake effectiveness can be multiplied by two just by adding the kit.[1]
The portal gear lift also decreases stress on the axle while increasing the torque of the machine. These two benefits provide a stronger more powerful machine. The stress is decreased on the axle by transferring the energy to the portal box and the wheels.[4] Decreasing the stress put on the axle is essential for allowing riders to have stability even on demanding rides. Riders often buy stronger axles after buying the portal gear lift to ensure optimal strength, but tests have shown this is not completely necessary. The portal box takes so much pressure off the factory strength axles they are able to manage rough rides.[1]
References[edit]
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 "How portal axles work". Leisure Wheels. 23 October 2017. Retrieved 17 December 2018.
- ↑ 2.0 2.1 2.2 2.3 "From Prototype to Portal Dominance - How SuperATV Built a Better Portal". SuperATV, LLC. Retrieved 17 December 2018.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 "Gear Reduction - A Quick Guide [How Portals Work] | SuperATV". www.superatv.com. Retrieved 17 December 2018.
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 Sagar, Thite; Mhaske. "Modal and Stress Analysis of Gear Train in Portal Axle System" (PDF). IJERT. International Journal of Engineering Research and Technology (IJERT).
- ↑ 5.0 5.1 5.2 5.3 "THE SURPRISING ORIGINS OF PORTAL GEAR LIFTS". SuperATV. Retrieved 17 December 2018.
- ↑ 6.0 6.1 Williams, Fred (1 August 2012). "Living With Mopar Portal Axles - 4-Wheel & Off-Road Magazine". Four Wheeler. Retrieved 17 December 2018.
- ↑ 7.0 7.1 "Unimog". Wikipedia. Retrieved 17 December 2018.
- ↑ Baker, Jeff (14 July 2014). "A Brief UTV History – Taking the World by Storm". RM Rider Exchange - The Rocky Mountain ATV/MC Blog. Retrieved 17 December 2018.
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