Looking for a Saturday Morning Cartoon with Lava Cannons

Question

I saw this episode (or maybe two in a row) on German TV around 1994 at a friend's apartment, and I haven't been able to track it down since.

• Western-style animated with "realistic" humans (as appear in the transformers cartoons)
• The heroes are besieged / under attack in their base, which is in a rocky desert-type environment
• They have multiple lava-cannons for defense, which are not working at the moment
• In order to fix these one characters dons a lava-resistant suit and goes into the magma-caverns underneath the base
• There is a walkway to a giant valve to activate the lava-flow. En route the walkway collapses, and the character has to walk through the lava and chart a course which is mostly safe (possibly with radio-support from somebody else)
• he makes it, turns the valve, and the lava-cannons repel the attackers / raiders.
• This might be the only time the base with lava-cannons appears

What could this be?

Answer 1

This is "Siege," S01E04 of Cadillacs and Dinosaurs (1993–1994).

In the 26th century, nature has spun wildly out of control. Cities have crumbled and the dinosaurs have returned to rule the earth. Jack Tenrac, one of the last of the "old blood" mechanics, along with his friends Hannah Dundee and Mustapha, defend humanity from the greedy governor Scharnhorst, freelance poachers, and other evil influences.

It's a post-apocalyptic animated series based on Mark Schultz's comic, Xenozoic Tales. The main character is Jack Tenrec, a mechanic with a passion for classic cars.

In this specific episode, Jack and his allies are attempting to defending their fortress from human attackers, but the flow of lava to their 'lava launchers' is shut off, so Jack has to traverse a gangway over a river of lava, wearing a bulky metal suit, in order to turn a valve and rectify the problem.

You can view the relevant sequence from around the 11:20 mark in the video below.