Tedward> "beef up a complete lack of suspension"<

... a real piece of geometry waiting to happen! ~Jon

Cavil,
correct also.
thank you,


the term is called "unsprung weight".

any vehicle must have some suspension to allow the dissapation of uncomfortable vibration. Even the most basic wheel and axle carts have some suspension...horsedrawn carriages place two leaf spring assemblies (or one large) beneath the bench seat.

Stiffness ( torsion in particular ) in a chassis leads to _predictable_ transfer-of-power patches beneath the wheels to allow control, but suspensions which are stiff do transmit vibrations into the driver and passengers which can become physically intolerable, especially at high speeds or on rough road.

It is also a good point that the energy required to reestablish the wheel patch to the ground after a bump, even a small excursion, must come directly from the fuel use of the powerplant. There is some exchange between the energy stored in compressed springs and gravity, called a Lagrangian integral, but losses in shock dampers and friction also come right out of the fuel use.

The issue of _Unsprung Weight_ (the sum of weights which are not above the suspension) reflects well in a model of a grandfather clock. Pendulums which are small require less power and work to maintain, while the mass and energy of a heavy and consequently lower frequency (read as 'more comfortable' ...[even safe]) demand much more power and consequently fuel to transport.

Leaving the heavy components of a drive motor directly on the wheel can only increase un-sprung weight, and remains a physical challenge that must be accepted with the decision to translate (move).