Engineering TV

The actual energy storage is in the gas in the bladder of the hydraulic accumulator.  Why not have a pneumatic hybrid?  Way back in 1930, a diesel-pneumatic was more efficient than a diesel-electric, and air is cheap and easy to store.

This is the most well executed production I have seen yet.  Good video, good audio, two cameras with interspersed clips of the product, well thought out questions, and enough time allotted to actually let your audience learn something.  Kudos.  Where do I send my resume?

Fantastic concept. What about oil leaks from the hydraulic systems and the resulting fire hazards? I have seen Industrial hydraulic systems over-time that tend to get leaky.  

Stewart, thanks for the positive feedback!  More to come from Lightning Hybrids this week and a few next week.  Every once in a while we'll do these in-depth productions on location - glad you like them!

Eric:

The Hydraulic Hybrid in this configuration is essentially a pneumatic hybrid as mentioned.  The energy is in fact stored by compressing air.  The air that is compressed is nitrogen gas which is held in the accumulator bladder.  The advantage of the hydraulic system is that you are pumping

an incompressible fluid which allows you to achieve higher flow rates in a smaller package.  A one hundred horsepower compressor that would allow you to compress and store enough energy to accelerate the vehicle from a stop would be half the size of the vehicle itself.  Imagine an industrial air compressor.  As I understand most pneumatic hybrid vehicles use a smaller compressor that runs continuously at a low power setting.  The one hundred horsepower hydraulic pump occupies much less than a cubic foot of space and only weights 45 pounds.    

Brian:

Certain types of seals work better than others.  If you are clever enough in how you design your manifold you can eliminate most of the hoses or piping in the plumbing.  By sticking to mainly o-ring and mechanical seals in the few seals that you have you can largely eliminate leaks from the system.  

We did, in fact have a hydraulic fluid leak during one of our test drives.  It was messy, but no more so, or more dangerous than a typical oil leak.