Ba$#~£d day, ba<*":d job.

[John Stevenson]

Fork truck motors often have a splined shaft that either drives hydraulic pumps or in the case of the older ones, direct into the gearbox.

These are integral with the shaft and either hardened on the teeth or toughened. The shaft cannot be pressed out and replaced without a full rewind on DC motors because the rotor part and the comm are separate.

Normal procedure is to cut the damaged spline off, bore the shaft out and stub with a new splined piece.

So what can go wrong ?

Answer is, at some time in the past this armature had been done before and a new stub pressed in and pinned. However some gorger had secured it with four 8mm [ 5/16" ] hardened dowel pins in a double cross formation, then welded then in.



Worn spline dropped back on the Armature after being cut off [ forgot to get a pic before hand but didn't know at this point the pins were hardened. ]



You can see where the pins were fitted and welded in.

That little cock up by whoever ? cost me about two hours extra, 3 triangular boring tips, 4 solid carbide end mills [ used but used as drills ]
Much cursing and swearing and forced me to go down the pub for a pie and a pint.

Stub not finally fitted at this point as it has to go across the road to the hardening shop but should get it back later tomorrow with a bit of luck.

[wierdscience]

Looks good as always John,what did you use for a cutter to generate the spline?Involute gear cutter or form tool?

[lakeside53]

Thought you'd retired? lol

[CarlByrns]

<snip>at some time in the past this armature had been done before and a new stub pressed in and pinned. However some gorger had secured it with four 8mm [ 5/16" ] hardened dowel pins in a double cross formation, then welded then in.

You just know as the guy was whacking those dowel pins in (with a 'eavy 'eaded 'ammer) he was thinking "What a great job I'm doing. This outta last forever. I'll weld 'em just to be sure."

[Arthur.Marks]

John, may I have a clarification on the term "toughened?" I mean, if it isn't hardened then what is it... forged? Maybe the term refers to case hardened (as opposed to through-hardened), but wouldn't that still be "hardened?" Perhaps it's an English colloquialism?

[John Stevenson]

Weird,
Hobbed them with a spline hob 10/20DP That's a modified 10DP hob that only cuts 1/2 as deep hence the 20 bit
Pressure angle is 30 degrees on splines as a rule I bought some spline hobs as they came up on Ebay for just this purpose

Lakeside,
The [email protected] won't let me retire, they still come knocking on the door

Arthur,
Toughened as in using steel that has been pre heat treated, Don't know what you numbers are but we can buy EN24 steel in different states of heat treatment There is plain EN24, EN24M which is easily machined and EN24T which machines nice with tipped tooling and right speeds / feeds and coolant
Get it wrong and it's like witches tits

[Edwin Dirnbeck]

Spline drives are usually bulletproof . What is causing this to fail .

[Arthur.Marks]

Ah - many thanks for the explanation. I understand now. That material in the US is often called "pre-hard" -- which is just as confusing, I imagine, as an identifier. Most common is 4140PH, which is a medium-carbon steel with a hardness in the 32HRC (Rockwell C) range.

[Mark Rand]

That's a direct equivalent to 4340PH for our colonial cousins. Lovely stuff in that condition. Turns like glued together spaghetti when soft and like rock when hard.


Did they pay enough to cover the work John?

[flutedchamber]

Spline drives are usually bulletproof . What is causing this to fail .

Possibly the female mate to it is worn and putting all the torque on the tops of the splines.

[john hobdeclipe]

My Dear Friend John,

In your second picture I can't help but see a bottle of some sort of "solvent" just in front of the blue handled hex wrenches.

What is it? Does it help? Or is it indeed a lubricant instead?

Just curious,

Your Friend John

[MTNGUN]

I never cease to be impressed with your efficiency, Sir John. If I attempted something like that it would take me a week or two.

How will your stub be attached ?

[gcude]

My Dear Friend John,

In your second picture I can't help but see a bottle of some sort of "solvent" just in front of the blue handled hex wrenches.

What is it? Does it help? Or is it indeed a lubricant instead?

Just curious,

Your Friend John

When John said, "Much cursing and swearing and forced me to go down the pub for a pie and a pint.", he was just being modest as usual. Looks like the repair may have taken more than a pint this time around.

[JRouche]

You can see where the pins were fitted and welded in.

That little cock up by whoever ? cost me about two hours extra, 3 triangular boring tips, 4 solid carbide end mills [ used but used as drills ]
Much cursing and swearing and forced me to go down the pub for a pie and a pint.

Ouch! So when you started hearing the "crunching sound" you had to be thinking "this job is gonna be a bad one". Bummer.

Curious? When you knew you were hitting something hard did you change your speed and or feed or go at it with the same drilling and boring plan?

You always amaze me with the work you do. Reminds my of my dear departed friend Del who owned a job shop. Everything and anything landed on his table. Never shied away from any job. Most of his mainstay was pumps and the like. Enjoy the pie and pint!!! JR

[jhe.1973]

Much cursing and swearing and forced me to go down the pub for a pie and a pint.

That's what made doing the job possible - it works in my shop too!

Nice work as always by the way.