Air Brakes

Last Tuesday I was heading out in the dumptruck to haul some manure.  The temperature was 20 above, which is cold for a diesel to start, and I had it plugged in.  The truck hasn’t run all winter, but it fired right up, and I thought I was in business.  The dumptruck only went about 100 yards, however, before it lugged right down – the brakes were setting up.

This is a heavy truck, and has air brakes.  It always takes awhile after being started for air pressure to build up enough to release the brakes, and there wasn’t a problem there.  But I hadn’t even used the brakes yet, and the gauge now showed that my air was all gone – and that automatically applies the parking brakes.

I walked all around the truck searching for an air-leak, without success.  I called the truck mechanic from Big Timber, who said he could be out in the morning.  That left me without a plan on a cold afternoon, with snow blowing on the breeze, and it seemed a good time to put together that proposal for another book publisher.

I tried to start the truck the next morning so that it could build air before the mechanic arrived, but it was just too cold.  I found the canister for the brake line anti-freeze and it was empty.  The weather had gotten worse in town, however, and the mechanic was swamped with towing and repairs – he couldn’t make it out until the next day.

I needed a new canister of starting fluid, and some brake line anti-freeze, so I went into Big Timber after lunch to buy them.  (Big Timber is a lot smaller than Livingston, but the road is much better).  After I installed the ether canister I was able to start the truck and find the leaking air-valve.  It was still only 20 degrees, but I lifted the dump box, propped it up with a fencepost, and removed the valve.

On Wednesday I took the valve in to the mechanic in Big Timber, and discovered that it was an old style – parts were scarce.  So I returned to the ranch, cleaned and lubed the plunger in the old valve, and reinstalled it.  It still leaked.

So I removed the valve again, polished the plunger with emery cloth, and lubricated it with oil.  But it was still hanging up.  Maybe replacing that O-ring would help.  I checked my assortment of O-rings, and found nothing that was close.

There had been an educational meeting in Wilsall scheduled on Thursday evening, and I had been vacillating about attending.  I could combine trips by stopping at the implement dealer for a new O-ring, then going on to the meeting.

But the implement dealer didn’t have the O-ring.  It would have cost about 14¢ if it had been in stock, but this size would have been special order.  He sent me on to the diesel mechanic at the truck stop near Livingston.

I’d only brought in the plunger out of the valve, but this mechanic assured me that he had complete valves in stock to replace whatever I had.  He put some special lubricant on the plunger that finally freed it up, and suggested that I bring in the whole valve.

On Friday I re-re-installed the valve, and it worked!  I was able to build enough air pressure to release the parking brakes and move the truck out of the road and back up to the shop.  But it was still leaking some.

Emma had a dentist appointment on Monday, so I took advantage of some warm weather on Sunday to remove the valve for the third (fourth?) time.  After dropping Emma at the dentist I headed out to the truck stop with the valve.  The mechanic quickly located a new generic valve, assembled the various plugs and fittings to accommodate my application, and sent me on my way. 

Today – Tuesday a full week later – it took only a half an hour to insert the new valve, tighten all the fittings, attach all the air lines, and fire up the truck.

It works! I have brakes!  And I am off to town to get a load of gravel!