# Triangular/Parallel four-link suspension system, how it works

I've been really interested at car suspensions lately and this particular system confuses me the most...

Are they simple hinges or do they also move other ways than that the angle they're placed or am I missing something here? Also, this video only makes it harder to understand.....

• The bottom one is easy: the links are parallel. The top photo shows a system that shouldn't work: when you rotate the two top links to vertical, they'd be much further apart than the connecting block allows. So this looks like it'd bind if there's too much suspension travel. May 4, 2017 at 12:17
• That's what I'm saying, @Hobbes... I just don't get it..... May 4, 2017 at 12:55
• also, in the parallel system, the shaft twists when one wheel is higher than the other.... How is that possible? May 4, 2017 at 12:58
• I disagree with the close vote: questions that lead to a better understanding of how a car works are valuable background for repair or maintenance issues. May 4, 2017 at 13:13
• It all about geometry and it works. Here is an excellent video that explains how it they are designed and work (lots of detail). May 4, 2017 at 13:23

The suspensions pictured are of the racing variety. They have small bushings in them making flexing difficult. This is probably why you have a difficult time with them. Racing suspensions are typically very stiff and so the suspension won't move much.

Both of these suspensions were used the the Ford Crown Victoria.

The picture above is an older Crown Victoria. It uses the triangular four link suspension. It's hard to see from the picture bu the bushings are quite large. This allows the wheels to move up and down in unison and individually. The advantage of such a suspension is that it controls both the up and down movement of the suspension but also the side to side movement as well. This is possible because of the triangular arrangement of the upper arms. The disadvantage being limited suspension travel. If you go rock climbing, this is not the suspension for you.

Above is a picture of a newer Crown Victoria. They switched to the parallel four link suspension. The travel of this suspension is grater than the triangular set up. I think the picture better illustrates the actual size of the bushings. Again, this suspension allows for wheel movement up and down in unison and individually. The Achilles heel of this suspension is that while it controls up and down movement it does not control side to side movement, particularly with big bushings. For controlling side to side movement you need a Panhard Rod or Watts linkage. The Crown Victoria chose the latter.

The Watts link is the contraption bolted to the top of the pumpkin.

• so those bushings also kinda help them twist aside from their hinge movements....? i kinda understand it better~ May 6, 2017 at 11:02
• Yes that's exactly it, with one caveat. The way the bushings are made the inner metal core and outer metal core are permanently fused to the rubber. This means that even the hinged movement is a type of twisting. May 6, 2017 at 11:18
• also, you've said that it's not suitable for rock climbing, but as far as I've seen, most rock climbers/bouncers use this type of suspension...... May 10, 2017 at 6:06
• It depends on what base vehicle you start from. May 10, 2017 at 9:29