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edwardlcy

brake pressure while towing c130 by a tractor.

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hi guys, just seeking your input regarding the sufficient brake pressure while aircraft is being towed? is it 1000psi, 1500psi or 3000psi? pressure buildup by manual pump or aux pump?

thanks

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edwardlcy,

Not sure if the job guides addresses this or not, and what I'm about to relay is from 15 to 20 years ago. The first choice was the APU or GTC/ATM and the aux pump. If the APU/GTC was not available, someone would have to operate the hand pump and maintain 3000 psi on the direct pressure gauge in the back.

Ron

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edwardlcy,

Not sure if the job guides addresses this or not, and what I'm about to relay is from 15 to 20 years ago. The first choice was the APU or GTC/ATM and the aux pump. If the APU/GTC was not available, someone would have to operate the hand pump and maintain 3000 psi on the direct pressure gauge in the back.

Ron

what about if towing from inside the hangar out to dispersal/bay? APU/GTC is not to be operated from inside the hangar right?

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edwardlcy,

You are correct no APU/GTC in the hanger we started it as soon as safely possible.

Ron

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I hope your Herk is not still sitting in the hanger while you are trying to figure out how to tow it from this web site. Gee, as a last resort have two guys drag the chocks while you move it out of the hanger then start the APU / GTC. That is standard procedure for moving it with no brake pressure. Bill :)

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Operate auxiliary system hand pump (3) until pressure on HAND PUMP PRESS gage (1) indicates

between 2900 and 3300 PSI. Maintain pressure throughout towing operation.

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Back in the day we used to pull them out of the hanger with a tug. The tug had breaks on them. Once out started the GTC.

None the less they didn't turn a wheel with less then 2200 PSI on the gauge.Did you ever have a shear pin in the tow bar break while under tow?The tug brakes do no good when that happens.Also the pictures show B models and later models.A model pump handle is to the right and just fwd. of the C/P seat.Pressure ind. is on the C/P inst pnl.

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None the less they didn't turn a wheel with less then 2200 PSI on the gauge.Did you ever have a shear pin in the tow bar break while under tow?The tug brakes do no good when that happens.Also the pictures show B models and later models.A model pump handle is to the right and just fwd. of the C/P seat.Pressure ind. is on the C/P inst pnl.

Never saw nor heard of a shear pin shearing. How far does a C-130 coast if the tow bar lets go? 3 feet? Five? Just curious.

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Never saw nor heard of a shear pin shearing. How far does a C-130 coast if the tow bar lets go? 3 feet? Five? Just curious.

The shear pin is located just a few inches foreward of where the tow bar fitting atatches to the nose gear.At least thats how it was in the early '60s.How far would the acft. coast? That depends on how quickly the brake rider gets on the brakes.Thats why brake pressure MUST be up for towing.When it happens and the tug driver applys his brakes and the brake rider dosen't the acft. will overrun the tug.This is not good. I never saw it happen but it could happen. What usually happend if it was to a new brake rider is he would slam on the brakes,the nose strut fully compresses,rebounds and the nose tires are briefely airborn!I saw it happen on 130s 3 or 4 times while I "was in" and saw it happen a few more times in the next 30 years as an acft. mech. on other acft. types.Man there was no end to the fun!

NOTE:2 reasons the shear pin could break on 130s.Just worn to the point of breaking or the NWS scissors link was not disconnected.

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Towing!!----This post brings back many fond (and not so fond) memories of my early days at Naha on the "tow,refuel-defuel" teams! I had forgotten how many "fun" ? times we had cruising around the flight line on the 4-wheel steering tractor/tug!

Things like checking out the "round-eyes" at the beach, crossing the active runway and trying to figure what the Ryukyan guy was saying in the tower. Also throwing a dirty black grease soaked chock rope into the cargo compartment and yelling "Habu"!!! and watching some of the guys jump out and run like hell!! Of course, a LOT of the time it was raining, or the wind was blowing hard!

Back to the subject---I had forgotten about manning the brakes and using the hand pump for pressure when we couldn't use the GTC. Of course don't remember the pressures!!! Also remember the tow bar--what a pain in the butt until you got used to it.

Thanks guys, for the memories,

Ken

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Yes sir that tow bar was a pain in the backside until you'd hooked it up a few times.But it was nothing compared to the 25 foot long bar used on test aircraft with a 12 foot long instrumented pitot tube with pitch and yaw vanes on it, mounted dead center in the nose of the radome.Hooking that badboy to the bird took some maneuvering.

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The shear pin is located just a few inches foreward of where the tow bar fitting atatches to the nose gear.At least thats how it was in the early '60s.How far would the acft. coast? That depends on how quickly the brake rider gets on the brakes.Thats why brake pressure MUST be up for towing.When it happens and the tug driver applys his brakes and the brake rider dosen't the acft. will overrun the tug.This is not good. I never saw it happen but it could happen. What usually happend if it was to a new brake rider is he would slam on the brakes,the nose strut fully compresses,rebounds and the nose tires are briefely airborn!I saw it happen on 130s 3 or 4 times while I "was in" and saw it happen a few more times in the next 30 years as an acft. mech. on other acft. types.Man there was no end to the fun!

NOTE:2 reasons the shear pin could break on 130s.Just worn to the point of breaking or the NWS scissors link was not disconnected.

The shear pin is actually a AN-12 bolt and it is the bolt that attaches the tow fitting to the NLG strut. This bolt allows tow weights up to 95,000Lbs. The torque arms, if not disconnected, has a limit of 30 degree turn limit or the black limit line on the fuselage just behind the nose radome.

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The shear pin is actually a AN-6 bolt and it is the bolt that attaches the tow fitting to the NLG strut. This bolt allows tow weights up to 95,000Lbs. The torque arms, if not disconnected, has a limit of 30 degree turn limit or the black limit line on the fuselage just behind the nose radome.

Correction- the shear bolt is an AN6-12.

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They call it a shear pin for a reason. The AN-6 bolt is rated at 8280 PSI shear strength. I have seen two break off. It keeps damage from happening to the NLG.

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Everything you wanted to know about towing a Herk but were afraid to ask. lol

Yes. I remember when I arrived at Pope PCS. The first thing I was asked was "Did you bring your own tow bar and pressure requirements?"

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Everything you wanted to know about towing a Herk but were afraid to ask. lol

From Lockheed Service News November – December 1956 page 12 , 13

Some early A’s used two NAS 517-5-5 screws for towing safety links. These two screws attach the tow fitting to the two arms coming from the nose gear strut.

also

The hydraulic hand pump was located on the floor next to the copilot’s seat.

No1.pdf

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