It would likely not scale up to higher rpm (maybe no more than 5k) and waste a lot of power compare to even push rod, let alone chain or belt. It is likely going to cost more too.
Gear Driven Overhead Cam Engines
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A gear drive system on a conventional engine will not and can not prevent valve float. If your valve springs are not strong enough for the application or the RPMs involved, you will get valve float regardless of how the cams are actuated.
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After reading other replies and links, the system you refer to is a different animal.
Spring Loaded Scissor gear "AKA" Anti Backlash gear. Toyota used them on many, many DOHC Timing Belt engines.....But as one gear turned the other without a idler gear in the mix, Only one gear needed to be Anti Backlash.
You have to lock the gear down before removing a camshaft as it will literally JUMP out of there if you don't
gear drive everything works great on big rigs and saves room
i have a car with a gear driven PS pump which is pretty cool
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Reason for no gear driven valve gear is no auto manufactures can or want to produce trouble free quality items any more. Even $60,000. engines like some Mercedes are pretty much disposable, one time use not easily rebuildable. Dependable quality items are not the friend of an auto manufacturing company where failure and major wear is highly desirable, so they can produce and sell more product.
Gear drive isn't needed for reliability, Chains & Belts are proven designs in light duty engines.
The Nissan ZD30 has a double scissor gear, one for the cam and one for the injector pump, on the same gear - you have a small window in the timing cover to get at it...and it's 50 turns before the marks line up again. That's another thing timing gears will have - a hunting tooth, so the gears don't always mesh in the same place. Triumph twins were 100 turns...easier to pull the idler out and start again.
Very cool piece of engineering.
Hard act to follow. While not an overhead cam, certain Ford Cologne 2.8 V-6 OHV engines had a gear driven cam. They showed up in the Bronco II and Capri II as well as some other applications.
Spring Loaded Scissor gear "AKA" Anti Backlash gear. Toyota used them on many, many DOHC Timing Belt engines.....But as one gear turned the other without a idler gear in the mix, Only one gear needed to be Anti Backlash.
You have to lock the gear down before removing a camshaft as it will literally JUMP out of there if you don't
Thanks for the explanation!
Crosley 4 cylinders had this config. My dad had Crosley outboard boat motors made by homelite, fisher-pearce, and bearcat that had the 90* shaft driven ohc.
Great thread!
does this shear the oil much ?
Mickey Mouse would approve (because of the shapes).
Didn’t GM use a phenolic plastic timing gear on the Iron Duke too? I think Toyota made a diesel V8 or I4 with a timing gear drive vs. a belt/chain.
I was told back when I purchased my 1996 Toyota Tacoma that the 2.7 four cylinder had gears. That was in response to my question of whether the engine had a timing belt or a chain.
Doesn't help that jt is very much a "fat guy in a little coat."
Absolute beast of a motor though. Here's a fun thread where one of the gears in the timing cassette have up and the guy fixed it himself:
https://www.clubtouareg.com/threads...the-distribution-of-a-touareg-v10-frex.73289/
I had one of those in a 1974 Mercury Capri. It was a great little engine and would take that little car up over 120mph many times over the few years I owned it.
The original specification for VW 504/507 was unsuitable for the V10 TDI, since it was a shear monster. So, at the intro of 504/507 there was a caveat saying the 5.0L V10 TDI and it's half size sibling the 2.5L R5 TDI were not suitable for 504/507, and advised to use a lower HTHS 506.01 instead.
Then later 504/507 got adjusted to that the gear driven TDI's were compatible for it.
****. When I thought I saw carnage from a Honda V6 jumping time, this is something else. One of pics shows a cavity in the V-bank almost like a Ford 7.3/6.0/6.4L PSD(Navistar T444E/VT365/MaxxForce7). VW does cool stuff but I feel they complicate and engineer for engineering’s sake.
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