Those Bull Gears are NOT made of bronze, the oil I used at the time was Union Gardol 50 wt recomended to me, was 1987 a lot has changed since then Spend the money and put in a synthetic 75-90 or better 75-140 you won’t be sorry ! 17afarmer

i was told they used bronze components in the final drive and bevel gear housings. the oil company rep told me dont use zinc fortified oils for that reason.

trainzkid88 wrote:

i was told they used bronze components in the final drive and bevel gear housings.
 

No way bronze gearing would take the loads put on a final drive. Bearing are either rollers/tapered rollers and ball. Maybe some ball bearings have a brass cage??
 

i cant remember if it was bushings or what it was i just remember being told there was bronze parts in there. bushings and shims are likely to be bronze.

some aluminium bronze alloys are so tough you cant machine them and they have to be forged, cast or ground.
mind you my machine is a d46u so larger or newer models are probably different.
and i doubt it was the oil itself that ruined his drive gears more likely that oil got contaminated in some way and the contamination did the damage. yes synthetic oils can give superior lubrication the main advantage being longer life and better resistance to severe conditions.

the only yellow metal i could find for the D4 was likely to be the old style final drive seal. and that was changed before the 6U came along.

The pinion gear reduction gear bull gears all metal, upper pinion reduction bearings are strait roller bearings bull gear hub is tapered roller have had quite a few apart never saw any bronze. 17afarmer

my 2 cents on Zinc as an oil additive... once again from my automotive background..

-Zinc was a common oil additive because it helped with extreme pressures/scuffing action, and helped camshafts/lifters survive with high lift, steep ramps, high spring pressures, high RPM in high performance applications etc...
-the environmentalists/treehuggers crowd frowned upon Zinc entering the waste system, not sure how toxic it is...? so it was slowly lowered, removed...
-most engines now use a roller lifter camshaft system so it became a non issue...
-not sure if Zinc had any other issues....i used to buy it as a oil supplement right from GM dealer...probably not even available anymore..

My understanding of why Caterpillar came out with the TO oils to use in transmissions and gear trains was that the engine oils had an additive that possibly made power shift clutches likely to slip more than they should, so they created TO oils of various grades to meet all the different climates, prior to this they had been recommending engine oils in all compartments.
i learnt to never exceed Caterpillar oil change periods, in fact final drives I always shortened the interval, in particular in planetary final drives, changed them every 250 hours, had finals lasting over 25,000 hours in D8L and I believe a D6HXl I sold on at 17,000, exceeded 25,000.

Clean oils, clean air and grease are the life of machine componentry.

Wombat

Amen Wombat,that's impressive hours of service...clean air, oils and fuel, filters, and no fear of a grease gun..