ASD use in Recreational Vehicles

ASD use in All Terrain Vehicles

Long a mainstay in the recreational vehicle market, belt type continuously variable transmissions (ASDs) are found in many ATV designs. Although this type of transmission has been successfully used within the snowmobile market, these belt type ASDs frequently fall short of delivering the performance and reliability that today’s ATV operators demand.

ATVs are often operated in all types of conditions and their transmissions need to keep functioning when riders take them through terrain where snowmobiles never go. The sealed, compact Orbital Mechanical Adjustable Speed Drive (ASD) provides ease of operation and reliability for the demanding conditions where ATV’s are designed to operate.

Pack Performance and Reliability into your ATV with a Orbital Mechanical ASD

Continuously variable transmissions are able to adjust the ratio between their input and output speeds like a geared transmission does, but they do so in a “step-less” manner with the following benefits:

  • Ratio change can be done under load
  • Ratio change occurs without the need to clutch and change gears so there is no interruption of power delivered to load
  • The prime mover (engine) can be set to run at the optimum rpm for power or fuel efficiency and the ASD ratio controls the vehicle speed instead of the throttle setting controlling the speed.
  • More control and performance options available to vehicle designers compared to the use of rubber belt type ASDs.

The ASD delivers performance and efficiency improvements over existing ATV transmissions as well. A compromise that belt type ASDs must typically be designed around is performance versus efficiency. The pulleys on a belt type ASD must “squeeze” the belt tight enough to keep the belt from slipping. However, if the belt is squeezed too tightly, frictional losses cause excessive wear and a loss of efficiency. Fail to squeeze the belt tight enough and the belt will slip, resulting in poor performance and, again, excessive wear. The automatic torque adjusting feature of the ASD delivers both efficiency and performance without needing to compromise between them. This automatic adjustment is accomplished without a horsepower robbing hydraulic or electrical control system.

Performance, reliability, efficiency: the ASD can provide the features that today’s ATV owners are demanding from manufacturers.

ASD use in Outboard Marine Engines

Boaters typically measure performance of their motors in two competing categories: “hole shot,” which is the power available to accelerate and plane off the boat, and overall top speed. As outboard engines do not have a multi-speed transmission like a car does, there is a constant compromise between a fast powerful start and hair ripping top end speed. The device at the heart of this compromise is the propeller. Using a lower pitch, the boat gets more acceleration on the low end, but top speed is reduced. Increasing the pitch provides a higher top end speed, but also increases the time to get to that speed and, more importantly, to get the boat on plane.

Typically, boats rely on the prop “slipping” while they are accelerating. This is part of the compromise where the prop pitch combined with the engine RPM and boat speed are at odds with one another. If a greater gear reduction existed between the engine and propeller (around a factor of 2), then the engine could deliver higher torque (and better acceleration) at a lower prop RPM. As a result, the whole system would be much more efficient. The Orbital Mechanical Adjustable Speed Drive is ideally suited for this application, and its highly compact, in-line design allows integration into existing outboard motor configurations without significant housing or drive shaft modifications.

How a Orbital Mechanical ASD Can Optimize Outboard Motor Performance

The ASD can deliver smooth, step-less shifting over its entire ratio range while the outboard motor operates at its maximum torque output. This delivers the motor’s full torque to the propeller at a lower rpm and provides the boater the hole shot of a low pitched prop. Then, shifting the transmission ratio as the boat planes off, the outboard motor is able to deliver high rpm to the prop and move the boat at a top speed associated with a higher pitched propeller. This allows the boater to choose his propeller based on top speed performance without compromising low speed power.

The Orbital Mechanical Adjustable Speed Drive can provide boaters with better acceleration and higher top end speed by allowing the propeller and engine to run at the optimal gear ratio for each condition.