Inside The Crowerglide Automatic Clutch

If you are familiar with the principles of operation of clutch mechanisms installed in mini-bikes or karts, then you will certainly understand the Crowerglide automatic clutch (AC) produced by Crower Racing Products .

Like those constructively simple clutches, the Crowerglide solution does not require the intervention of a driver and its operation principle is based on engine RPM and load, and while the basic concept here in many ways reminds a conventional foot-operated/pedal clutch (PC), ACs provide some advantages for particular types of drag racing cars.

ACs can hardly be considered as a novelty, since these solutions have been used in drag racing cars for a long time. This product is also known as a slipper clutch, because the discs of this clutch are made of graphite and other different materials. These discs are designed to slip and eventually come close to lock-up. In some drag racing classes like Alcohol and Pro Mod engineers prefer to use PCs or torque converters in their cars, while Nitro dragsters tend to use ACs like the Crowerglide.

Nitro applications require every launch being the same, so the car will react identically, making it more adjustable. When utilizing a PC and on one pass you load it a little harder than on the next one, the result won’t be the same. The Crowerglide AC solution eliminates any possible drivers’ errors related to the clutch use. The Crowerglide clutch is notable for its adjustability, it can be tailored to different situations depending on the hp parameter and the application. Moreover, it can be equipped with additional discs or weight on the arms, or springs.

In fact, since a driver simply stabs the throttle to speed up, it doesn’t matter how hard drivers press on the clutch pedal or how consistently they release the clutch pedal from one run to the next. Therefore, it is no wonder that the Crowerglide clutch and similar automatic solutions find application in drag racing nostalgia fuel, mud racing, in motorcycles or in some other applications that do not need linkage.

One of the most vivid benefits of using the AC in a Nitro Car stems from the fact that Nitro is extremely susceptible to loading on the starting line when it is staging. Thanks to the AC, it is possible to set the clutch up for a mechanical amount of load regardless of the driver’s actions.

Become familiar with peculiarities of the Crowerglide clutch design

Now let us compare the Crowerglide clutch with a conventional pedal-operated clutch (PC).

In comparison with PCs, an AC, as has been mentioned before, excludes any drivers’ mistakes in clutch control and it operates a bit smoother. The main shortcoming of the Crowerglide product is the fact that you cannot start off at any RPM rate. The maximum possible RPM could be as low as 4,500, but when we are talking about the PC, you may be able to get away with an additional 1,000 RPM. When it comes to price and wearing capacity, the pedal-operated and ACs are quite comparable and their reliability directly depends on the operating conditions severity level.

The AC is a little more complex and more time-consuming when it comes to its adjustment, as the air clearance has to be set up correctly by putting clearance gauges in, in contrast to the much simpler pre-load adjustment on a PC. It should also be borne in mind that a PC is actuated when the pedal is not depressed, while in case with an AC the situation is the opposite — the air clearance remains until the engine reaches a required RPM.

What about differences and similarities between an automatic clutch and a torque converter?

It should be noted that in terms of mechanical structure both mechanisms are quite similar: their operation directly depends on the engine RPM rate, slipping up to a point of partial or complete lock-up. But other than that, torque converters (TCs) considerably differ from ACs. To begin with, the main peculiarity of a TC is its capacity to multiply torque when the output RPM is so low that it allows ATF coming off curved vanes of the turbine to be deflected off the stator, while it is locked against its one-way clutch, thus providing the equivalent of a reduction gear. A clutch, in turn, has only two states – it either slips or locks up. Secondly, the ATF inside a TC, exposed to high temperatures, still operates as a coolant for the internal TC parts. At that, an AC is incapable of performing cooling.

Check out the interview with the representative of Crower Racing Products

All in all, it is important to emphasize the fact that all the mechanisms described above have the same purpose: to bring the power into engagement or disengagement between 2 running shafts. But when it comes to a particular class of drag racing, engineers use the most appropriate option for a specific engine or fuel type, even when the power level is similar.