Yes, naturally an extra truck (two extra axles) reduces the axle load but
it comes at a cost and cost determines the outcome of many tram purchases.
I once saw an Alstom advertisement that actually promoted the "virtue" of
the cheaper cost of its three-truck trams. I wish I'd kept a copy because
it must have taken the prize for sheer chutzpah. Nothing about the extra
costs that the system's maintenance engineers would have to deal with in
years to come.

PTV = "You can't fool us".
TfNSW = "Wow, a cheaper tram!".

Tony P

On Saturday 23 March 2024 at 14:14:30 UTC+11 Mal Rowe wrote:

> On 22/03/2024 16:52, TP wrote:

> > I've no doubt that there are design issues on different models of

> > trams that have a bearing on the problem.

>

>

> Axle loads are a key issue.

>

> In Melbourne, the fixed truck D2s have a maximum axle load of 22.2 tonne

> (for the centre truck - 11.1 tonne per axle)

>

> The Es are longer and heavier but have four swivelling trucks with a

> highest axle load of 17.4 tonne (for an end truck - 8.7 tonne per axle)

>

> The Cs have a quite high axle load - around 21 tonne per fixed truck -

> fairly evenly spread across the trucks.

>

> One of the key specs for the E class was for a lower axle load than the

> C and D classes.

>

> Mal Rowe - getting technical

>

>