I just got a quote on a Boomer 3040 tractor with a factory CAB and was told the cab model only comes with the CTV transmission. Being new to this I would like to know how the two transmissions differ in operation and what are the Pros and Cons. I have an HST transmission on my Cub Cadet but have never owned something with a Constant Velocity Transmission.
Thanks in advance!
There are some folks that post here at TBN who can explain in technical detail how both HST and CVT transmissions work. I can't give you all those details, but here's a summary that might help you get started, at least.
1. HST... Instead of using a series of transmission gears and shafts to transfer force from the engine to the drive wheels like a standard gear setup, the HST drive uses the engine to drive a hydraulic pump which feeds fluid to a hydraulic motor that makes the wheels turn. The advantages: clutch is no longer required, continuously variable "gear ratios" by using a simple foot pedal control valve to control the flow from pump to motor, easy changing from forward to reverse. The disadvantages: the hydraulics aren't as mechanically efficient as a gear drive so some power is lost, same issue means it's not the best for extensive heavy tillage work, and the whole thing is more complicated than an old fashioned gearbox.
2. CVT... An innovative gearbox design that achieves the same continuously variable gear ratio advantages of HST using mechanical means. Supposedly operates with higher mechanical efficiency than HST.
Don't know enough to comment on disadvantages.
HST has been in wide scale use in tractors for more than 30 years and seems to be basically as reliable as conventional gearbox transmissions. Just my opinion, but each depends more on how it's used than one being inherently better than the other. CVT is more recent, particularly in smaller equipment, and does not yet seem to be at the same stage of technological maturity (again, just an opinion... others may not agree). It seems to be a promising new approach, but there may be some teething issues still being worked out. HST's are probably the most common setup in tractors under 60hp today and are widely available from the leading manufacturers; I think NH is the only manufacturer with a compact CVT tractor so far.
I'd invite you to check out both types and come back to TBN with your observations. I'm sure that would bring on a lengthy, animated thread everyone would enjoy and learn from. And good luck with your tractor shopping adventure!
