Recently, in Moab, Utah, a new Jeep Cherokee climbed onto the worst and most dangerous zone called "Hell's Gate" in the area. This is a compact design similar to a station wagon, with a four-wheel drive vehicle. The vehicle uses an electronically controlled differential, an elastic suspension, and requires a high level of proficiency for the driver's driving skills. Off-road enthusiasts are very surprised that such a small "city" vehicle can climb here.

"The automotive world leads us to think about traction, maneuverability and braking in different ways," said Brad Allen, vice president of marketing, product management and engineering for Terex's aerial work platform. "In the field of off-road equipment, we call it For'off-road performance'". In this regard, Mr. Brad Allen conducted a series of exploration and analysis of off-road equipment from the perspective of the historical evolution of motor vehicle power, suspension system, traction and driving force and the practical application of aerial work platforms.

"Thirty years ago, this type of off-road vehicle was only a fanatic among car enthusiasts; you would either choose a two-wheel drive and no traction control car, or choose a large "4×4" vehicle, which has a large Sized tires, heavy-duty transmission system and anti-skid differential. This car helps us think from different angles because they have developed cars with four-wheel drive and traction control. They can’t drive in the deepest mud pits, but it’s fascinating. Surprisingly, they are very adaptable and can adapt to all kinds of terrain that are not very bumpy." Mr. Brad Allen said, also in the past ten years, drive technology has promoted the development of aerial work platforms, power, suspension systems and traction control. Is the key factor among them.

Power: the pursuit of horsepower

A few years ago, in order to understand the requirements for traction and power of aerial work equipment, Terex’s aerial work platform engineers, after a lot of theoretical analysis and practical work, found that going up steep slopes and driving in deep mud pits had an impact on power. The requirements are the most demanding. For example, when driving in a partially frozen mud pit with a depth of at least 30 cm, the tires are extremely difficult to drive. Large boom-type aerial work platforms or off-road scissor-type aerial work platforms require more powerful power, but for only more than 10 cm deep The ordinary mud pit does not need such a big power.

According to the driving experience of most people, driving a car rarely requires full horsepower. Similarly, aerial work platforms rarely require full horsepower. Advances in technologies such as stall prevention devices and hybrid systems have reduced the size of the engine. There are two main types of hybrid power systems: series and parallel. The series hybrid power system is essentially an electric aerial work platform with a diesel engine or a gasoline engine on-board. The power of the diesel engine is only used to charge the battery, and the maximum power output to the wheels comes only from the less powerful electric motor. For the parallel hybrid system, the diesel engine is directly connected to the wheel drive motor, so that the power of the diesel engine and the electric motor can be combined systematically, and the diesel engine with less power and higher efficiency can be used to drive the machine. At the same time, Electric motors can provide more powerful power for climbing and rugged ground. The electric motor doubles as the engine and can charge the battery at the same time, thus providing more powerful power for the device.

Traction control: contact point speed is zero

Traction control uses mechanical, hydraulic, or electrical systems to effectively obtain power from one sliding or rotating wheel, and then transfer the power to another wheel placed on the ground. The drive system engineers of aerial work platforms, like their car-making counterparts, have spent countless hours to ensure that the speed of the tires is always zero. For many years, people have used mechanical methods to achieve this requirement, such as the use of solid shafts and non-slip differentials. In the late 1990s, the technical development of hydraulic systems began to provide traction control in hydraulic transmissions through integrated diverter valves, and this gradually became the norm for aerial work equipment.

In the latest technology, the sensor of the direct drive electric machine is used to detect the running state of each wheel, and then the power is transmitted to the appropriate electric motor, so that the traction control reaches a whole new level. The core of traction control is an AC direct drive motor that provides professional traction control software. This kind of traction technology is the most basic among a variety of new cross-country aerial work platforms, and is only applicable to the technology of large four-wheel drive equipment.

Four-wheel drive capability level: four levels

Only considering the "Slab or RT" equipment selection criteria will result in waste of costs on the job site. People should think about the appropriate equipment according to the level of four-wheel drive capability. Now such equipment can be divided into the following four levels:

Level 1: Slab type-Slab type devices are two-wheel drive and occasionally single-wheel drive. They have no traction control and can only be used for fast movement on flat paved ground. The Slab type device used to include only scissor aerial work platforms, but now it can be applied to upgraded mobile aerial work platforms, such as the Genie® IWP™ series super aerial work platforms with power wheel assistance.

Level 2: Slab type with obstacle crossing ability-such as the Genie® GS™ series aerial work platform, which has two-wheel drive and usually has limited hydraulic and traction control between the left and right wheels. They can overcome small obstacles and climb hills.

Level 3: Off-road type-Off-road equipment can cope with a few inches of mud pits or soft gravel roads, snowy roads, and material piles, and can cross most obstacles and climb mountains easily. Such devices are relatively new and have only gradually developed in the past 5-10 years. They include many four-wheel drive devices with fixed axles and low-tech traction control and two-wheel drive devices with swing axles and electronic traction control. The application of this new technology effectively allows the power to be output to the wheels where it is most needed. A parallel comparison shows that a two-wheel drive device with a swing shaft and the latest AC traction balance drive technology can easily outperform a four-wheel drive device. The Genie® GS™-69DC scissor aerial work platform is an industry-leading product with this type of technology.

Level 4: Heavy-duty off-road-large tires, powerful engines and large vehicles are used in extreme situations. Deep mud pits or large obstacles require this type of equipment. Large four-wheel drive boom aerial work platforms and large platform scissor aerial work platforms, such as the Genie® 90 series scissor aerial work platforms belong to this category of products. The current heavy-duty RT equipment may soon be surpassed by four-wheel electric direct drive equipment with electronic traction control.

The most suitable equipment: choose according to site needs

When assessing the needs of the job site, the difference between off-road and heavy-duty RT vehicles is small, but it should not be ignored. When off-road equipment can deal with all aspects of the field, choosing a heavy-duty RT machine means higher cost investment. Therefore, it is very important to understand the needs of the work site and choose the right work machine.

Mr. Brad Allen affirmed the development prospects of off-road aerial work platforms, "The Jeep Cherokee I saw in Moab changed my view of the vehicle’s off-road capabilities. I believe driving a vehicle with the latest technology, AC drive, and adaptability An aerial work platform with a terrain condition will also make operators have similar ideas. Off-road aerial work platforms provide operators with a lighter and more cost-effective machine. Unless they are indeed in heavy and extremely rugged terrain. , Otherwise, an off-road aerial work platform that is suitable for most application conditions will have more stable performance than a typical four-wheel drive vehicle that lacks a swing shaft or traction control."