Table of contents
- PS reader questions about motorcycle technology What is a dog ring gear?
- PS answer:
- It is common practice in car transmissions
- “Dog ring” is new German for shift sleeves
Kawasaki
6th pictures
Cook
1/6
PS technology expert and motorcycle whisperer Werner “Mini” Koch is constantly tinkering and tinkering himself in his own workshop, and no technology topic is too confused for him. And if he doesn’t really know what to do next himself, he knows exactly where to ask.
Cook
2/6
CLAW GEAR
The transmission input shaft [1] transfers the power to the output shaft [2]. The chain pinion is attached to their teeth [3]. A gear pair [4] is available for each gear. When changing gears, the shift drum [5] rotates about 45 degrees. The milled grooves [6] move the shift forks [8] mounted on a shaft [7].
Cook
3/6
HRC SEAMLESS TRANSMISSION
The gear wheels (gray) are each connected to the shaft via two load pawls (green = engine torque) and counter-load pawls (red = engine braking torque). Springs (blue) activate them, the tappets (yellow) unlock the teeth.
The delicate handles transmit 260 hp. There are two loads in each gear-
pawls (green) and counter-load pawls (red), two tappets (yellow), coil springs (blue) and four shafts (gray) installed – a masterpiece.
Cook
4/6
DRIVE GEAR
The construction of the old Maico RS 125 gearbox from the 1970s is similar to that of the Honda RC 213 V. …
Cook
5/6
… Here, too, all six idler gears and the internal gearshift mechanism are located on the output shaft.
Kawasaki
6/6
DOG RING GEAR
In the Kawasaki H2 six-speed transmission, the gears on a transmission shaft produce the frictional connection. However, it does not shift the gears, only the dog rings, which are guided by narrow and light shift forks.
counselor
workshop
What is a dog ring gear?
PS reader questions about motorcycle technology
What is a dog ring gear?
Content of
Do you have a technology question that has been on your mind for a long time? Everyone in the forum claims something different? Are you at your wits end? Then put your question to PS. We get to the bottom of the matter, explain the connections or ask industry experts or racing teams.
Werner Koch
05/12/2015
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“Hello PS, in the review of the Kawasaki H2 I read about a Dog Ring gearbox that is supposed to work like MotoGP. Is that another name for seamless??”
PS answer:
A transmission is a complex structure and the answer is therefore correspondingly complicated.
The classic claw gear consists of an input and output shaft on which the gear wheels sit. A pair of gears is available for each gear stage. Since these are constantly in engagement, these pairings must each consist of a fixed and an idler gear. Loose gears are not permanently connected to the shaft, but rotate freely on needle or plain bearing bushes on the respective gear shaft. The frictional connection to the shaft is established by the neighboring fixed gear, which moves laterally and engages with the claws in the counter claws or recesses. Fixed gears are further subdivided into rigid, non-displaceable or milled or pressed-on gears and the so-called sliding gears, which can be moved axially on the shaft by the shift forks on an internal toothing.
The disadvantage of the claw gear: The relatively heavy gear wheels, often designed as a double wheel, have to be shifted axially on the toothing in a flash. To simplify this process, Kawasaki installed the so-called Dog Ring gearbox in the H2 engines. The frictional connection between the gears and the shaft is established by means of shift sleeves, which, as with the dog gear, are also moved axially via a shift fork and shift shaft. However, these shift sleeves are significantly lighter and therefore faster to move than entire gears. In addition, the drivers (claws) can be made finer, which makes shifting smoother.
It is common practice in car transmissions
However, the Kawasaki’s shift sleeves are not that new. In car transmissions, they are commonplace, including the so-called synchronizer rings. Harald Bartol’s 125cc and 250cc KTM racing two-stroke engines also had such dog rings for power transmission. And of course all BMW motorcycles with helical gear wheels.
Because of the side force generated by the helical gearing, the shift forks would have to fix the gear wheel axially in its position. The shift forks would not be able to cope with this, as these steel run on steel and are therefore exposed to high friction. Which is why worn or defective driving pins in conventional dog clutches ensure that the gears slide out of their position against the resistance of the shift forks. Consequence: The shift forks shrink a lot and literally glow out after prolonged use. There is a risk of capital damage.
“Dog ring” is new German for shift sleeves
In the Dog Ring designs, however, the quiet helical gears could be implemented without any problems, as the gears are axially fixed on the shaft and the shift sleeves, known as “Dog Ring”, create the connection between the transmission shaft and the gear. And to be clear: the new Dog Ring gears are not seamless gears either. It will be a long time before this design from MotoGP flows into the series, because the fine mechanical works of art require regular maintenance in order to keep the delicate pawls and the associated control mechanics running reliably (see picture gallery above).
The so-called draw-key gears of many 50s mopeds from the 60s and 70s were constructed in a very similar way, but only switchable with an interruption in traction. Narrow, compact and sorted without internal teeth on the gear shaft, a pawl or balls in the shaft block the freewheel and thus establish the flow of power to the rear wheel.
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