Do Shopping Carts use Positive or Negative Caster?

[Dibbons]

According to this two-minute youtube video, at the end the expert explains that shopping carts turn very easily but won't go straight very well because they have a lot of negative caster:


However, according to this internet article, shopping carts have positive caster and that is why they like to travel in a straight line and don't turn well:
https://cartreatments.com/negative-and-positive-caster-symptoms/

Someone here must have their story backwards.

 

[R/T Boy 67]

Positive

 

[69a100]

They never track straight as the frames are always tweaked.

 

[FrnkNsteen]

Sorry..... Got distracted by something on that first post..... What were we talking about again?

 

[Aeronet]

I don't think they have either since caster is an angle and shopping cart wheels are just bolted on and don't have a relationship to a steering mechanism.

 

[KENTON]

Shopping carts have + caster

 

[greycharger]

I was driving down I 90 going east just past Murdo, South Dakota and I see a man pushing a shopping cart down the shoulder. The shopping cart is piled high and looks like it must have everything he owns in the world. Without much to look at on the plains of South Dakota I start wondering about the man and the shopping cart. How much weight can a shopping cart handle? How many miles does he get out of a set of wheels? How far was he going? Was his last stop at Kmart on the east side of Rapid City where he took shopping carts for test drives to find one that ran smooth and straight?

 

[Lefty71]

Shopping carts have + caster

Erm, till you put them in reverse lol

 

[Kern Dog]

The casters are NEGATIVE because the wheel centerline is behind the attachment point of the swivel. The "forks" are curved backward. Compare this to a motorcycle where the front wheel sits forward of the point where the forks attach to the frame.

 

[69a100]

The casters are NEGATIVE because the wheel centerline is behind the attachment point of the swivel. The "forks" are curved backward. Compare this to a motorcycle where the front wheel sits forward of the point where the forks attach to the frame.

I don't know which one it is? But there's a Military fighter jet that has the Fwd. landing gear like that.

 

[R/T Boy 67]

If a line is drawn through the steering axis to the ground, and that point is forward of the tire contact point, then the caster is positive. Shopping carts and motorcycles are both positive.

 

[oldbee]

Crap, too much weight at the front from beer causes all the problem! I forget caster/camber every other day!

 

[Aeronet]

Ok. I looked at a picture. Since the wheels swivel they could be either. They do have a caster.

 

[Aeronet]

I guess that's why they are called casters.

 

[Kern Dog]

If a line is drawn through the steering axis to the ground, and that point is forward of the tire contact point, then the caster is positive. Shopping carts and motorcycles are both positive.

They are opposite. The motorcycle wheel mounts forward of the "axis", the shopping cart wheel sits behind it. How can you not understand this?

 

[Aeronet]

The motorcycles have positive caster. The shoping cart in the picture is negative caster.

 

[conv67bdere]

I'm positive . . . that the shopping carts don't give a rats one way or another . . .

They're usually so messed up that they pull right or left, or have that annoying flat spot on one tire that make it go thump, thump, thump so the whole world knows you're coming . . .

( sigh ) . . .

Minor adjustment . . . the ONLY time that the stupid things track "true" is when it's barreling through the parking lot and aiming for your CAR . . . DENT ! ! ! !

 

[R/T Boy 67]

Before you insult my intelligence, you should do a little research on what caster is. There is plenty of information out there. That shopping cart has a lot of positive caster, and those springer forks have very little, if any. All modern motorcycles have positive caster. My earlier description is accurate.

 

[Kern Dog]

I agree that the motorcycle DOES have positive caster, just as ALL new cars and trucks have it. The shopping cart wheels are the opposite. The wheel axle is behind the mounting position of the forks.
Look again. If the forks pivot/swivel/rotate forward of the wheel, the caster is negative.

 

[Aeronet]

No. The motorcycles in the picture have positive caster. The picture of the shopping cart shows negative caster
FSMs from the 60s call for negative caster on manual stearing gear boxes because it is easier to turn. You lose stability. Think motorcycl for stability.