Spring Landing Gear

[SkyPirate]

Drilling for the roll pins but avoiding the gun drilled part of the gear

[HighWing]

I was told by a staffer at Grove that my gear is a Hammerhead because all Grove gear has drilled holes with pins. Apparently Hammerhead was an earlier supplier.

My first Model IV changed over to Hammerhead gear in 2000 after about 200 hours from the original bungee gear. The gear did have the roll pins (See attachment).

A brief history as far as I recall. Two guys started Grove - much like the two guys who started Kitfox. Then much the same, the two guys decided they had different ideas as to which way the company should go - or something. The guy that split off (Hammerhead) was the developer of the gun drilling method and machinery. The reason I went with Hammerhead was that the gun drilling came standard with the gear whereas Grove charged extra. Again, much like Kitfox/Avid, Grove survived for the long term while Hammerhead ceased operations several years after the split.

Early on the alloys were different as well. Hammerhead used the 7075-T6 where Grove used a different alloy - not sure which one, but Grove would repair and re-heat treat the softer alloy at no charge for a while. That service was not provided by Hammerhead, but 7075-T6 is almost impossible to bend in the T6 condition. For some time now Grove has gone to the 7075-T6 exclusively.

[mr bill]

Aluminum alloys can be bent, using appropriate bend radii for that alloy, it's temper and it's thickness, without cracking, assuming all bends are across the grain of the metal and depending how new the metal is. Freshly quenched can be bent using a shorter bend radius, but as the metal ages, it hardens and requires a larger bend radius. 7075-T6 or 2024-T3 would require a very large bend radius (for a landing gear, it would be measured in many inches).

[SkyPirate]

I think grove manipulates the gear before heat treating to T-6 specs,..for spring gear it's a slower cooling process then for hardening, not sure on a quenching sequence,,it's been too long since I messed with that part of it..

if I remember right you can bend it prior to heat treat up to 80% of material thickness for Radius so minimum would be 1.25"R on anything from .375 .. to 1" I forget the formula for larger then 1" thick
.375x100/80%=1.25"
.875x100/80%=1.25"
less then 3/8" -.375 can be 100% thickness at Radius

or do I have that backwards bill?

ok I just remembered..it's been way too long since I messed with forming larger metals..you add 80% of the thickness to the length of the blank to get the right dimension after the bend..

proof that if you don't use it you loose it

[SWeidemann]

Another thing about my gear is that it is held in place with rectangular shaped blocks that do not look anything like the units in the build manual.(Drawing shows an assembly that includes round gear rocker disks...not mine.)

Skot

In communicating with a young lady at Grove, she came up with the conclusion my gear was made by Hammerhead. She said all Grove gear has the pins. At any rate, my intent is to get my hands on a set of roll pins, drill the holes and put them in.

St

[mr bill]

In the case of 7075 alloy, bent in the 0 condition 1/2" thick (90 degrees) requires a bend radius of 4 times thickness. In the T6 condition it requires 10 times the thickness. Heat treat after forming may not be practical for large parts like landing gears. Bend radius of 45 degree bends can be significantly smaller.

[SkyPirate]

yes that's it Bill,..I was figuring 45 degrees or less,..and using at least a 6" bottom die and a round nosed upper die at least 2" on upper