Jagdtiger number of track pairs and track tension

[Chang]

This topic was started in David Brady's thread on 23 March 2023, and carried on here as per advice:

How many pairs of track are used in your JT? The number quoted in the Assembly Manual is 48 for newly built JT, and maybe less after running.

Yet in my half-built JT , 48 pairs of (right) track is too slack , even after adjusting of the Tension Arm to it's forward (ie, to maximum tighten the track) position.

The right Tension Arm in most forward (ie, to tighten the right track) position.

1-6 JT-102.JPG (142.47 KiB) Viewed 4926 times

The right 48 pairs track still too slack.

1-6 JT-100.JPG (187.69 KiB) Viewed 4926 times

On the other hand , 47 pairs of (left) track is too tight , after adjusting of the Tension Arm to it's backward (ie, to maximum loosen the track) position.

The left Tension Arm in most backward (ie, to loosen the left track) position.

1-6 JT-101.JPG (164.48 KiB) Viewed 4926 times

The left 47 pairs track still too tight.

1-6 JT-99.JPG (194.35 KiB) Viewed 4926 times

Regards,
Lerh Chang

These users liked the author Chang for the post:
mark lawson

[Chang]

by DaveMacri » 25 Mar 2023, 01:41

I know I had posted this resolve for the lack of adjustability on the King tiger idler-figured it would be the same on the JT too. As pictured I had a new arm machined with more swing to it. With removing a track link set you have approximately 2" which is too much and then the tracks are way to tight and can cause damage to the drive. The custom machined idler unit gives the ability to bridge that 2" gap and worked perfect on my KT.

ATTACHMENTS

63856542149__64AC2075-D24D-4997-BCA6-B0FB3ADBD133.jpeg

1-6 JT-103.jpg (88.62 KiB) Viewed 4924 times

63854665400__11E88868-4AFB-4B9A-9E82-31CD74EE7398.jpeg

1-6 JT-104.jpg (72.35 KiB) Viewed 4924 times

63854645101__EA6C8AB5-8FD2-4E49-B36D-93C58301421E.jpeg

1-6 JT-105.jpg (97.09 KiB) Viewed 4924 times

These users liked the author DaveMacri for the post (total 7):
Klaus Uschkurat, Gary Rafferty, Oliver Brüninghaus, Chang, Michael Allen, David M Wilks, mark lawson

[Chang]

by Chang » 25 Mar 2023, 11:16

Hi Dave,
Good to see this custom machined idler unit can solve the track tension issue. Wish it is still available for JT builders.
Do you have the contact details of this machinist ?

With regards,
Lerh Chang

These users liked the author Chang for the post:
Steve Lewington

[Chang]

by Chang » 28 Mar 2023, 18:59

I replace the LHS stock 90mm tension screw with a 100mm one. Cut the tension Arm material a bit to increase the moving range, and put them back like this :

See both the tension screw plate and tension arm are cut to add the moving range. Also tap more threads on the longer tension screw.

1-6 JT-107.JPG (165.2 KiB) Viewed 4922 times

I then add the LHS track back to 48 pairs of link , the track now looks like this :

The track tension is still not enough.

1-6 JT-106.JPG (220.56 KiB) Viewed 4922 times

I think I need similar Idler unit like Dave Macri's.

These users liked the author Chang for the post (total 2):
Klaus Uschkurat, Steve Lewington

[Armortek]

Keep in mind that as the tank is run the track links and pins will bed in and the length of the overall chain will increase. At this point you will be able to remove a track link pair.

[Chang]

Do the same thing on RHS of the Idler unit and the track. Looked OK :

1-6 JT-108.JPG (146.75 KiB) Viewed 4781 times

1-6 JT-109.JPG (165.84 KiB) Viewed 4781 times

In the future , after running test and bed in , then to remove a pair of track link , as per Armortek's advice.

[Chang]

Few more photos :

Internal looking backward of the Idler units.

1-6 JT-110.JPG (111.9 KiB) Viewed 4779 times

Look higher.

1-6 JT-111.JPG (134.72 KiB) Viewed 4779 times

Internal looking forward.

1-6 JT-112.JPG (132.86 KiB) Viewed 4779 times

External front view. The travel lock is still a long way to go.

1-6 JT-113.JPG (158.45 KiB) Viewed 4779 times

[Brian Ostlind]

Is the speaker location shown in the manual or is that your position?

[Chang]

Is the speaker location shown in the manual or is that your position?

My idea. But maybe not a good one. Will relocate in the future.

[Chang]

(Deleted.)

[Armortek]

To : DaveMacri, PM sent to reply you. Thanks.

Gents - we have seen a few posts similar to this one lately.
Please note that when you send PM, the recipient will get an email informing them of the fact. The PM will remain in your "outbox" until the recipient has read it. There is no need to post that you have sent a PM.
If a few days go by and you still see the PM in your "outbox" then it is acceptable to post a message on the forum.

[Chang]

Bench test of the LHS track. The noise near the ldler wheel was caused by track hitting the sponson.
Need to reduce the number of track links and the height of Idler wheel later, after "bed in" done.



Regards,
Lerh Chang

[Chang]

A damage caused by myself:

One of the Elevation Pivot (CT0411) was stuck in the hole of the Gun Sleeve (CT0404) and Slew Pedastall (CT0405).

1-6 JT-114-2.jpg (157.9 KiB) Viewed 4425 times

The whole assembly had already done a while ago, and can manually move the gun barrel up and down smoothly.
I should have not taken them apart and tried to re-assemble them again by adding a flat washer in between.
All trying to unlock it were failed, and the threads of both CT0404 and CT0411 are damaged.

1-6 JT-116.JPG (85.1 KiB) Viewed 4425 times

Now I need to re-order these 3 parts.

[Chang]

(Deleted)

[Dale jordan]

Hi Chang is it a grub screw ? try heating it up and re cut the slot with a hacksaw It should come out if not a grub screw it can be re taped and new pivot made Dale