Railfan Technology > Independent brake pressures

I have found a GP15-1 running with composition brake shoes on a standard Blomberg truck 1 shoe per wheel with 35 lbs pressure. I know this is too low but what is it on your road with this type of locomotive.It should be 75 lbs with composition shoes. What are the pressures on all locomotives I believe I know but I a might need corrections some rebuilds have different pressures or different configurations.
Mike

Ya seems low...should be at least 45lbs for any unit. Think the J1.6 relay valve is working correctly...assuming it has one?



Edited 1 time(s). Last edit at 11/06/09 18:22 by KV1guy.

I didn't look to see which valve was on it. Would have to be a JI.6 wouldn't it?
Mike Wikman

Tallowpot Wrote:
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> I didn't look to see which valve was on it. Would
> have to be a JI.6 wouldn't it?
> Mike Wikman

Well, you won't see the J 1.6 valve unless you can get into the air brake compartment below the engineer's seat. You will see a 26L brake valve inside the cab bolted to the control stand.

The Independent Application and Release mu hose line is charged to 45 psi whenever the brakes are applied and 0 psi when the brakes are released. The maximum pressure is 45 psi which was the standard independent pressure applied to the brake cylinders. When the railroads wanted a different pressure applied to the cylinders due to the size (diamater) of the cylinders or the advent of composition brake shoes the IAR line pressure stayed the same but a 'multiplier' J valve was installed on each locomotive. A j 1.6 valve increases the pressure it senses in the IAR line by 60% to the cylinders. Thus a 20 lb IAR pressure becomes 32 lb to the cylinders on the locomotive brakes. A full independent application puts 45 psi in the line and the brake cylinders on locomotives with the J 1.6 valve get 72 psi. So a mixed consist with GP38-2 units with composition brake shoes and GP9 locos with cast iron shoes when stopped with the full independent applied would show 45 psi in the IAR line, 72 psi on the air gauges of the GP38-2 and 45 psi on the GP9.

Baldwin locos had a different brake pressure as did some of the EMD locos with Flexicoil trucks with the brake cylinders located low and between the wheels of the trucks.

I would say the pressure on you GP15-1 are lower than standard which is sometimes done to reduce wheel sliding and expensive to repair flat spots on the wheels for units used in yard and local service. The FRA would take exception if this is the case. The gauge could also be bad which again is something the FRA will cite the company for.

Tallowpot Wrote:
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> I have found a GP15-1 running with composition
> brake shoes on a standard Blomberg truck 1 shoe
> per wheel with 35 lbs pressure.
> Mike

Hard to get flat spots with 35 lbs?

be caraeful!!!!
if the shoes are CLASP shoes (that is 2 shoes per wheel, or 8 per truck) )then 35psi X2shoes =70PSI
It would be low if there was only one shoe per wheel