ABI Scott 3200 tailwheel - bent vs. straight control arms

[briantrani]

I'm considering buying the Alaska Gear Company ABI Scott 3200 replacement tail wheel for my 1947 Cessna 140.

A friend has a 1946 140 with actual Scott brand tailwheel with steering arms bent up 90 degrees.

1946 140 with Scott Bent Steering Arms.jpeg (32.11 KiB) Viewed 6832 times

One of our members has a great post and installed a Scott 3200 with flat steering arms.

association members scott straight steering arms.jpeg (81.82 KiB) Viewed 6832 times

The Alaska gear company sells both styles.

bent arms.png (28.62 KiB) Viewed 6832 times

My question is - which should I order? flat or bent?

I'm told we are looking for a set-up that keeps the steering chains parallel with the leaf-spring when it is loaded. It's difficult to determine that without having both to try. Your help on this topic is appreciated!

[briantrani]

straight.png (30.54 KiB) Viewed 6831 times

[6643]

The Scott wheel listed on the TCDS had straight arms.

[meloosifah]

You want the straight ones.

[edidin]

Have the straight arms.

Which end do the springs go on? The yellow rudder in this thread has the springs at the tailwheel arm; most I've seen are the other way around.

[6643]

The installation instructions are available in the Resources section of the main web side at the bottom of the documents page. That said, some folks feel that the springs are better placed at the tailwheel end to prevent them getting tangled up in the tailwheel spring apparatus.

There are also a couple of articles in the Neal Wright Technical Articles section of this forum.

[briantrani]

Thanks everyone so far! After reading the replies I was getting more convinced to order the straight arms.

I was perusing the resources on the forum, including the Type Certificate Data Sheet (thanks for that tip).

The only thing is - now I found this drawing in the resource section with tips covering the Scott tailwheel. It shows the Scott with the steering tabs bent upwards on page 3.

early 120-140 Scott 3200 installation drawing.jpg (2.27 KiB) Viewed 6631 times

My SN: 12448 was Manufactured 1-21-47

I can see how the type of spring flat, single, or double bend would change the geometry of caster... and relationship of how parallel the steering chains are with the leaf spring. I also need to purchase a leaf spring (my incomplete leafspring is a double bend and the wrong one from what I've read in the forum). I've been planning to purchase the single bend spring.

At any rate, I appreciate further discussion on this topic of bent vs straight control arms and spring style before I purchase either of these.

Thanks folks. P.S. I have attached the full Scott document where I found the above drawing.

[6643]

I think you are misinterpreting the pictures. None of the pictures in that file show the arms with the bent tips. What you are seeing is the arms which are not exactly flat. On the 3200 the complete arms are slightly bent at the base whereas on the 3400 the tips of the arms are bent vertical.

Univair lists the ABI-3224A as an approved replacement for the 3200. It has the "heavy duty" bent arms. I'm pretty sure that when it was Scott the only wheels with the bent arms were the 3400 series, which was not an approved replacement for the 3200. (The 3200 is the approved part for the 120/140.)

None the less, the TCDS lists the Scott 3200, and when it was written, the 3200 had the "straight" arms. Why argue with success?

"Straight"


"Bent"

[briantrani]

Thanks, John. I see what you mean about misinterpreting the drawing. I appreciate you taking the time to help me understand this.