< Midterm Test Run >
The test run was carried out on a private layout owned by a club member, constructed with the OS dual tracks with 7.5-meter radius curves. The engine with the carrying case was transported from the car trunk to the track by four men.
The engine was placed on the track using a rerailer modified from the Hunslet use, with crossbeams upgraded from M6 to M8 thread.
The boiler had been pre-filled with deionized water in advance. I started firing with wood chips immersed in paraffin, followed with coals.
Due to the substantial capacity and firebox size, steaming up was a hard work. It takes significantly more coals than the Hunslet. When the boiler pressure reached to 0.2 MPa, I halted the electric blower and started steam blowing.
Upon careful inspection around the boiler, no leaks were found. However, water drops were observed from the water gauge drain valves and the cylinder drain cocks. The leak from the cylinder drain cocks persisted even after closing the regulator valve and the drain valve. It indicated leaks in both the regulator valve and the cylinder drain cocks.
After the safety valve blew, opening the regulator, the engine unceremoniously started running. I confirmed the loco could pass through the 7.5-meter radius track. But the running resistance considerably increased at the curve. I drove the engine to and fro and noticed squeak noises. Lubrication around the driving wheels stopped the noise.
Another obvious problem is the slipping of the driving wheels. The weight of the completed C53 will be around 150 kg and the axle weight might be half of it. The current weight is 120 kg and the axle weight is around 50 kg. I think it's insufficient to draw the heavy engine and tender with the driver.
Regarding the firing condition of the firebox, the flame concentrated in front of the grate. It suggested uneven air supply from the ashpan.
Video clip of the test run --->
Despite these problems, the loco ran safely. So I regard the loco passed the test.
To modify the regulator and the ashpan, I removed the boiler from the engine again. The ashpan and smokebox are heavily smeared with ash and soot.
First, I modified the slide valve of the regulator to eliminate leakage. The left one is the old and the right one is the new. They are views from the bottom. I increased the size and cut a recess in the bottom to reduce inside pressure, so that the valve is pressed on the valve seat.
I also replaced the coil spring of the plunger with a stronger one to enhance pressure on the valve. With these parts, the regulator was assembled again. Incidentally, I didn't care about the cylinder drain cocks, because I cannot identify currently the bad ones.
Next, I closed the front opening of the ashpan to decrease the air supply from the front of the ashpan. A typical ashpan for a model locomotive has only a rear opening, but I followed the prototype that has air damper doors both in front and rear. Finally, I closed the front opening. Before the change on the left photo, after the change on the right photo.
Regarding the water gauge drain valve leaks, the nuts for the cocks were slackened. So I tightened them.
After these modifications, I executed the second test. There was no obvious leak from the regulator. The leak from the water gauge drain cock decreased but still existed. I have to change the manner itself to a needle valve, for example. Concerning the ashpan, the flame in the firebox looks uniform and I feel the boiler power was improved.
During the test run, I identified the defective cylinder drain valves and checked them. There were cutting chips between the ball valves and the valve seats. Maybe the rinse after cutting the cylinder block casting was not perfect.
Anyway, there was no critical issues. So, once I finished the test run and resume the building