Microheli T-Rex 450 front shaft, gear and pulley set
Written by Ashley Davis Sunday, 25 September 2005 00:00
Front PulleyThe following is a review of the MicroHeli front shaft, gear and pulley set.
Initially let's take a look at the component:
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As can be seen from the pictures above the front pulley is a CNC machined pulley which sits on and is secured to the shaft via a grub screw. The bearings on the shaft are of a similar quality and design as those found on a stock front pulley assembly. The pulley itself comes with some assembly instructions which detail the use of an extra spacer when fitting this component to an XL T-Rex, this just raises the height of the pulley slightly.
First impressions when opening the packet and looking at this component is that it is a very well engineered piece of equipment and cannot fail to improve upon the stock component it is designed to replace. The top pulley for driving the tail belt will clearly run with less vibration than the plastic item found on a stock T-Rex. This should help reduce vibration which can be caused by out of round gears quite commonly seen on the stock unit. Additionally the lower blue gear is also CNC machined and so will be perfectly round. The blue gear is made of delrin and so will also be extremely tough and hard wearing. The shaft for the gear and pulley is also a larger diameter than the stock one, which should make it more crash durable and less likely to bend. MicroHeli have also designed their system so that the bearings no longer need to be glued to the shaft (unless you fit to a Heliup frame as I did, in which case the bottom bearing needs to be secured on the shaft to stop vertical play of the bearing in the holder. Although this is only to stop the bearing from falling out rather than the shaft being able to move. You could glue the bearing in the holder but getting it out for maintenance would be problematical, where as removing the bearing from the shaft could be achieved with a pinion puller).
I checked the fitting of this component to a standard frame set and as you might imagine it is a perfect fit. I also checked to see if this component could be used with the Align carbon frame. Unfortunately the Align carbon frame comes with a prebuilt tail drive assembly which I couldn't see how to get apart in order to fit the MicroHeli upgrade part. This was rather disappointing as I currently have a fraying tail belt which I am sure is down to poor moulding quality of the tail belt drive pinion on my Align Carbon Frame.
Faced with this problem I fitted the MicroHeli upgrade to a Heliup carbon frame in order to give it a high performance test on one of my high voltage machines. Since fitting I have flown two flights of 3-D with emphasis on tail rotor heavy maneuvers. The upgrade part has performed as expected without any issues or requirement for maintenance.
I didn't expect to notice any improvement in flight characteristics from fitting this part, it isn't designed to affect flight performance but should help with long-term wear and tear on the tail belt. This upgrade will now undergo longer term testing to see how it copes over a broad range of flying.
Conclusion
This is one component of the T-Rex that for some time I have expected an upgrade to become available or alternatively it be replaced by a higher quality component in the stock kit. MicroHeli have produced a very nice drop in replacement for the stock unit and for anybody who has suffered from a fraying tail belt this may well be a worthwhile upgrade. Additionally if you have a vibration on your tail that is proving hard to track down this upgrade might well be the solution you are looking for. Personally I like all the components on my own machines to be smooth running and free from vibration, so this is a welcome upgrade from my point of view. Whether this component is a necessity really depends on how well you feel your existing system is working. If you have no issues with excessive belt wear or have a vibration free tail system then this upgrades is not going to offer you anything that you haven't got already.
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