Camshaft and Tappet Reuse Guidelines. November, 1999

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eService Bulletin

Subject,;

Camshaft and Tappet Reuse Guidelines

BulletinNo. Date:

3666475

Camshafts (Cast Iron)

November 1999

General Information:

This bulletin applies speciflc visual inspection criteria for B & C chillad ductile iron or chillad casI iron camshaft materi

with the flat-sliding tappets. The photographs will help, as reference tools for inspection and comparison of the sampl

cam lobes and for ranking the testad cam lobes and for determiningthe percentage of the usefullife lefton the camshaf

and tappets.

This bulletin addresses the deterioration of cam loba surfaces at the ramps, edges, and cantar of the lobes. Cummins

Distributors and Dealersare encouraged to use their technical expertise to implement the guidelines for low-cost a

high-quality repair of Cummins producís.

Definitions:

- }

. Pitting: Loss of a piece of material from the loba, resulting in a hola that is visible to the naked aya. Pits typical

haya rough, dark bottoms andsharp edges and usually occur in the heavily lo.aded areas of the cam nose

near the edges ofthe cam lobes. .

. Chatter: The axiallilJes that run parallel with the axial of the cam lobes. The chatters break down and distu

the oil fi,lmthickh~$s.lt Gould cause the metal to metal contact between cam lobeand tappet running surface

whichincreasesthe cam loba wear ratas andpotential for cam loba and tappet pitting failure. ,,'

. Distress: A localizad roughening of the surface that does not extend to any significant distance below the l

surface.

. Maco-Spalling: Very larga pitting. A larga local area loss of material from the cam loba surface.

Guidelines:

* Do not reuse the camshaft ifthe angina isbeing overhauled or ifthe camshaft isout of the angina for any reas

This bulletinis a supplement to the applicable angina family troubleshooting and repair manual.

Cummins Engine Company, Inc., Columbus, Indiana 47202-3005Cummlns Englne Company LId., Daventry, Northants, England NN11 5NURegisteredOffiee:46-50CoombeRoad, NewMalden,SurreyKT34QLRegisteredNo.573951EnglandCopyright @ 2000CumminsEngineCompany,Ine.AIIrightsreservad

Paga 1 o

RankilJg , Reuse Estimate..%of camshaf

Conditionof LobeliferemainingScale .

O New cam loba, neverrun No restriction 100%

¡. 1 Normal polish,likenew Unconditional reuse 90%

2 Heavy polish wear, few pittingless Unconditional reuse 70%than 2 mm indiameter

3 Heavy wear and larga pitting areas atConditional reuse * 50%cam nose area

4 Heavy wear and multiple largar pittingReplace Less than 30%

areas atcam nose ,

5 Veryheavy cam loba wear and camReplace

I

10% or less

loba heavy pitting and galling



Camshaft and Tappet Reuse GuidelinesPaga 2

Tappets

General Information:

This bulletin applies specific visual inspection criteria for B & C sliding tappets when running with chilled ductile iron,chilled cast iron, and steel éamshaft materials. The photographs will help as reference tools for inspection and

comparison of the sample tappets and for ranking the tested tappets and for determining the percentage of the usefullife left on the tappets.

This bulletin addresses the deterioration of sliding tappets at the running surface. Cummins Distributors and Dealersare encouraged to use their technical expertise to implement the guidelines for low-cost and high-quality repair ofCummins products.

Definitions:

. Pitting: Same as cam jebe pitting, the running face of the sliding tappet loses one or many small pieces ofmaterial from the running face of the tappet, resulting in a hole that is visible to the naked eye. Pits typically have

rough, dark bottoms and sharp edges and usually occur in the heavily loaded areas of the tappet.

. Scuffing: The running face of the tappet is galling and the material is removing at a high rateo The running surfacewill lose the material.

~stress: A localized roughening of the surface that does not extend to any significant distance below the tappet" surface.

. Maco-Spalling: Very large pitting. A large local area 1055of material from the running surface of the slidingtappet.

Guidelines:

* Do not reuse the tappets if the engine is being overhauled or if the tappets are out of the engine for any reason.

This bulletin is a supplement to the applicable engine family troubleshooting and repair manual.

Ranking Condition of Tappet Reuse Estimate % of tappetScale life remaining

O New taooet, nevar run No restriction 100%

1 Wear oolish, like new Unconditional reuse 90%

2 Normal polish wear, few pitting less Unconditional reuse 70%than 2 mm in diameter

3 Heavy wear, multiple pitting, wave Conditional reuse * 50%wear pattern, rouah surface distress

Excessive wear, multiple larger pit-

4 ting, scuffing, edge chip out, surface Replace Less than 30%porositv.

5 Very heavy wear, scuffed, heavy gall- Replace 10% or lessing, tappet breaking



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Camshaft and Tappet Reuse Guidelines. November, 1999