LM-3 vs LM-4

[mickey]

In the G scale, what exactly is the difference between these?  I have 2 of the older 3 and 5 of the 4’s. Before I select which engine to install them are there significant differences?

[William Brillinger]

According to Ring Engineering:

August 2022, New Product - RailPro LM-4S-G
The LM-4S-G adds analog control and higher voltage capability for our G scale loco modules.

You can compare the manuals here:
https://ringengineering.com/RailPro/Documents/LM-3SGInstructions.pdf
https://ringengineering.com/RailPro/Documents/LM-4SGInstructions.pdf

[mickey]

So in my case, installing on a number of different Bachmann engines, like the Shay, 3 truck Shay, Climax, 2-6-6-2, Heisler each with 2 motors, I should use the LM-4 and save the LM-3's for the likes of the 4-4-0, K27, C19, Rail truck and AMS Goose due to possible juice requirements?

[snowdog]

The basics are that the LM4s are for scales larger than HO. It is designed to work with higher input voltages and current draws the larger units need. An LM3 will probably burn up in a G-scale unit!

[William Brillinger]

The basics are that the LM4s are for scales larger than HO. It is designed to work with higher input voltages and current draws the larger units need. An LM3 will probably burn up in a G-scale unit!

Snowdog: There is a G Scale version of the LM-3. It's call the LM-3S-G. It was replaced by the LM-4S-G some time ago.