by Paul Crowe on 2/12/2013
in Motorcycle Design, Motorcycle Technology
Did you ever wonder what Norman Hossack would have done if he had designed a front wheel drive system on a motorcycle using his suspension? Well, some years back, he had been working out the plans for doing just that, he even calculated the additional weight involved, but couldn't find a suitable CV joint to meet his needs. His dream was to build an AWD Dakar bike because he thought it would be unbeatable.
Norman Hossack design for a front wheel drive system
Norman Hossack design for a front wheel drive system
Norman was reading our article on the Lawson AWD KTM with a Hossack front suspension and thought we might like to see the plans he had drawn up years ago as another take on what could be done. The drawings here are actually the ones he was going to submit for a patent, but he wasn't ready to spend the time and money so never went ahead with it.
There are a lot of similarities to what the Lawsons designed, but handlebar placement is obviously different as well as the design around the CV joint, the Hossack style suspension seems well suited to mounting the necessary extra hardware and can be adapted in more than one way. Maybe someone should try their hand at building another one with Norman's own design.
You might remember the Hossack square piston engine Norman shared with us a little while back. I guess once you get the creative design spark, it just never quits. I love seeing these designs, I thought some of you would, too.
I've included the description and more images Norman was going to submit with the front drive patent below:
FRONT WHEEL DRIVE MOTORCYLE SUSPENSION SYSTEM.
ASTRACT
In a motorcycle front wheel suspension system the front wheel is mounted by a support axle to an upright unit which slopes to the rear and is in turn mounted to the vehicle chassis via two wishbones (A arms). The attachment between the up right and these two wish bones is accomplished with ‘ball joints’ which allow for the suspension to turn to the left and right as well as ride over undulations in the road. Also mounted to this upright is an axle shaft which supports a constant velocity joint and a chain drive sprocket. This sprocket drives a chain which transferees drive to the front wheel via its own sprocket. Drive is transferred to the outer element of the constant velocity joint via a chain drive from the engine of the motorcycle via a series of guide pulleys. As the wishbones are pivotally attached to the vehicle chassis the arc they provide creates a constant distance between the chassis and the upright. Therefore the drive is transferred to the upright along a path that is substantially in line with and between the two ball joints and positioned in such a way as to keep the chain tension constant. The final chain which transfers drive to the wheel can also be tensioned and the tension maintained because the components are all part of the same housing.
TECHNICAL FIELD
This invention applies primarily to motorcycle front systems though is not confined solely to them and may apply to other vehicle forms that would benefit from a driven front wheel.
TECHNICAL PROBLEM
The normal method by which the front wheel is mounted to a motorcycle is through a sliding telescoping structure commonly known as telescopic forks. In this structure the turning function of steering the vehicle is achieved via a steering head and the bump function is accomplished by this telescoping component. The steering head usually requires large bearing assemblies rigidly mounted to the chassis and a sub assembly to which the telescoping tubes are rigidly mounted. Both of these structures make it very difficult to pass drive of a mechanical form to the front wheel. At the steering head this drive would have to cope with the left/right turn and then this drive would have to pass to the front wheel which would be at a varying distance depending on the ride condition.
In a motorcycle front wheel suspension system the front wheel is mounted by a support axle to an upright unit which slopes to the rear and is in turn mounted to the vehicle chassis via two support structures here knows as wishbones. These wish bones are joined to the upright structure via ball type joints or universal type joints
Lawson KTM All Wheel Drive Conversion in Action
by Paul Crowe on 2/4/2013
in Motorcycle Builders
Several months back, we showed you Marty Lawson's AWD conversion on a KTM 300 EXC. You'll remember the front wheel drive system was designed and built by Marty Lawson and his dad, the telescopic forks were replaced with a Hossack style setup and then a chain drive was added running to a sprocket up front.
The first tests looked very promising and Marty just sent me an update with a couple of videos of Pete Laubmeier giving the bike a workout in the CWIRA Moose Endurance ice race and another running through some turns and over logs out in the woods.
Didn't find any dramatic advantages to AWD on the ice when using studded tires. Except for hole shots. The bike almost always wins the race to the first corner. At the same time, it wasn't any slower either. The bike was more settled in corners with a bit of power. Pete could get on the power a little sooner on corner exits. The bike could also use different lines around corners without losing speed.
Then out in the woods:
The bike really hooks up in the soft sand. The best part of the video are the log crossings. When Pete crosses the log slowly, he is demoing a technique anyone could use to cross logs.
Marty says they're taking the bike to the Chicago motorcycle show next weekend and entering it in the competition in the performance custom class, so if you're in the area and planning on going, you'll be able to get a close look at the bike and maybe get a chance to ask Marty a few questions.
It seems to me they've got it working really well and when you realize this was a home designed and built DIY project, it's just that much more impressive. This is a project Marty and his dad can be very proud of. I like it.
Fuentes http://thekneeslider.com/hossack-front- ... n-hossack/
http://thekneeslider.com/lawson-ktm-all ... in-action/
