The Moulton Hydrolastic suspension was first featured in the Morris 1100. This photo shows Alex Moulton with Alec Issigonis, who famously designed the Mini, at the lauch of the 1100 in 1962.
In the background, is a chart detailing the design of the Hydrolastic suspension unit.
The Hydrolastic was a rubber suspension unit with integrated fluid damping. It was important for two reasons. Firstly, whereas a conventional suspension used separate springs and dampers, the Hydrolastic combined the two, thus saving space.
Secondly, the front and rear units were interconnected by a small diameter pipe, to reduce the tendency of a car to pitch when it went over a bump.
The Hydrolastic suspension was used in several cars from the 1100, to the Rover 100 and Metro. It was originally intended to be featured on the Mini, but wasn't quite ready when the Mini was launched. The first Minis with Hydrolastic suspension were produced in 1964.
A new implementation of the Hydrolastic suspension concept is currently in use in the Moulton New Series bicycle. Here, the fluid damped rubber unit contributes to the ultra smooth suspension.
The stiffness of the rear suspension can be increased for heavier loads, by pumping air into the valve at the rear of the unit. Earlier New Series models also featured a valve on the side of the Hydrolastic unit for adjusting the fluid damping, but this is not a feature of recent models.
Photo credits: Ken Butterfield and Alex Moulton Bicycles.
AFAIK the pressure has no significant influence on the damping and/or stiffness, it is needed to keep the fluid were it should be. Thereofre the actual pressure does not matter in a wide range.
In the video, The Innovative Engineer, AM indicates that the air pressure valve is provided to increase the stiffness.
It seems the hydrolastic suspension works well with the Moulton Bicycles that have a unified rear triangle but I question how useful it is on the older AM space frame bicycles where the rear triangle is not unified and the rear suspension often, reacts if one does not accelerate in a precisely defined manner.
Where can we can we get new replacement hydrolastic displacers??
I need a couple for a Riley Kestrel 1300 MkII manufactured in 1969;
Where can we can we get new replacement hydrolastic displacers??
I need a couple for a Riley Kestrel 1300 MkII manufactured in 1969;