# Help wanted with HLW Mack power block



## Bill Martinsen (Mar 4, 2008)

I have a power block (motor block) from a Hartland (HLW) Mack 4-wheeled loco. I'm thinking of using it to power a 1:13.7 scale loco. To do this, I need to change the wheels to Sierra Valley Enterprises 7/8ths wheels. I don't want to take the stock HLW wheels off the stock axles until I'm sure I can replace them with wheels from SVE. So, I've got a few questions.

What does the worm gear and axle look lke once the wheels have been removed?
Can I somehow replace the stock axle with a 1/4" diameter steel axle?

Thanks in advance for your assistance.

Bill M.


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## Stan Cedarleaf (Jan 2, 2008)

Bill, check with Phil Jensen at Hartland parts. 402 571-2933

He's there Tuesday and Thursday mornings 9-1 Central time. He should be able to give you a good rundown on the Mack Motor Block.


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## Bob Baxter (Jan 3, 2008)

I recently used a Hartland "Mack" power unit in my Toonerville Trolley project. I'd never tinkered with one before that job. I knew that they were just about bullet proof so it was an easy choice. When I started looking for a way to add a crank mechanism I discovered the secret of their wheel attachment is very simple. The shaft is a plastic material and is tapered. The wheels have a matching taper and it is a simple press fit. I don't feel that different wheels can be adapted to replace the originals. There must be a different block that would work for you.


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## Bill Martinsen (Mar 4, 2008)

Thanks for the tip, Stan. I had a nice chat with Phil Jensen at lunch time and he was very helpful. The whee-axle-gear arrangement is very similar to that used by HLW on the Woody drive unit. The plastic axle slips through the plastic gear. A flat spot on the axle and one on the inside of the gear keeps the gear from spinning on the axle. The wheels slip onto the plastic axle and are retained by circular clips.

I began to disassemble the wheel-axle-gear arrangement by slipping an end-cutting Exacto blade between each wheel and the little clip that retains the wheel on the axle. Using a light hammer, I tapped a few times on the Exacto knife handle and cut off the end of the axle. After doing this to all four wheels, I pulled the wheels off the axles and slipped the axles out of the two gears. The 7/8ths (1:13.7 scale) wheelsets from Sierra Valley come with 0.25" diameter axles, which happens to be the same size as the hole through each worm gear.


I'll report on the re-assemble procedure once I have the Sierra Valley wheelsets in hand. 


Bill Martinsen


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