Model YTH 18542 Mandrel Assembly

[platefire]

YELP! When you get to changing the bearings out separately, that's beyond my pay grade>>>>>may need to
go off on a week long bearing seminar to do that

 

[SeniorCitizen]

YELP! When you get to changing the bearings out separately, that's beyond my pay grade>>>>>may need to
go off on a week long bearing seminar to do that

If you can tie boot laces ya can replace the bearings . There's only 3 pieces inside the assembly and all will go in either end first .

 

[bertsmobile1]

OK,
Let's clear things up for ones & for all
There is no such thing as a water tight bearing they simply do not exist without external seals .
A rubber seal bearing has a rubber seal, with the LIP POINTING IN to prevent the grease getting out not to prevent anything else other than dirt getting in
Pop one off and old bearing and look at the lip
Nest there are various types of seals
Grease seals like you have on your front wheel bearings and water ( or liquid seals ) like you have on a pump and in between them are oil seals like the ones on the engine crank shaft designed to prevent oil leaving the engine .
They all have different constructions and different fits , or tightness on the spinning bit if you like .
If a 2 RS bearing was water tight then you would not be able to jamb your finger in the middle & turn the outer race, there would be too much resistance .
Now we get to metal shields
They are designed to prevent debris getting INTO the bearing from the outside but they do not prevent the grease getting out from the inside
SO if you pump a spindle with a ZZ or Z bearing fitted with grease then eventually it will ooze out through the shield
This tends to make them water tight as the grease repels water.
If you fit a 2 RS bearing into a spindle then pump it full of grease then usually the bearing will pop out because the grease can get from the spindle into the bearing past the rubber seal but it can not get out of the other side of the bearing and in fact is a recognised method of no damage bearing removal if you have a fast high volume grease gun

The other big difference is the metal shield is held tightly in place so the pressure of the grease acting on it will not cause it to to shift inwards or deform to touch the cage where as a RS will .

So take awys is if you want to fil the spindle with grease ( which I do ) then at least 1 bearing has to be either open or a metal shield and because of gravity it is best to have it on the top because the air will accumulate on the top so can be expelled the next time you grease the spindle along with any water degraded grease around the bearing.
Z or ZZ bearings will usually substantially outlast a RS bearing if the spindle is kept greased .
My commercial customers have been trained to give each spindle 1 stroke of the grease gun to all spindles every week and those who follow this rule have never experienced a spindle bearing collapse and in most cases their spindle bearings last for a very long time
I have several Z masters in the run and they are supposed to run open bearings with grease seals but the seals cost more than the bearings so I now fit ZZ bearings to the spindles and most of them have gone from 2 sets of bearings / year to one set every 2 to 3 years .
Nad remember commercial mowing contractors have to mow in the rain in many cases and their mowers live on their trailers, most of which are parked on the street overnight or in a drive so they cop a lot of weather .

 

[platefire]

Thanks, I've read through your explanation several times trying to absorb all the info. Haven't had any experience
with different types of bearing seals and how they work. I'm assuming "RS" is rubber sealed and not sure about ZZ or Z type(metal sealed?). Seems like what experience I have had is like in a housing like a spindle Mandrel
is getting the old bearings out that sometimes requires a puller tool. Then if you start beating to pull old or install new you end up tearing something up. When you change these kind of things out on a regular basis it's easy but
if you never have, its a big old bear:>)

 

[bertsmobile1]

leave the blade on remove the pulley nut & pulley, they usually come off easy
Slip the nut back on 2/3 of the way so it is not flush with the end of the spindle
Put a drift onto the end of the spindle and give it a good whack
The shaft will drop out a bit. loosen the nut a bit more & repeat
Just before you get to the last turn of the thread the spindle will fall out taking the bottom bearing with it
Poke a long drift in from the bottom & tap the top bearing out.
Support the bottom bearing some how & remove it from the shaft
Fits
The bottom bearing is a light press fit on the shaft and a hand press into the housing so you use a piece of water pipe to tap the CENTRE of the bearing home before returning it to the spindle
The upper bearing is a sliding fit on the shaft and a light press fit into the housing so it goes into the housing first then the spindle gets passed through it .
Usually I chill the spindle then warm ( in the sun light ) the lower bearing and it will usually push on by hand
I chill the top bearing and it falls into the spindle housing and it is allowed to warm up while I chill the spindle with the lower bearing on it.
And again they will usually slide in. occasionally needing a little tap

 

[platefire]

OK Thanks, I might just try doing the bearing change out when the time comes and use this thread as a
reference. Other question I have is from past experience in removing the mounting bolts that hold the Mandrel
assembly in place usually break off when you try to remove them! For the normal hack mechanic
like me, that pretty much renderers the housings un-useable

I guess pre-treating the treads with penetrating oil might help that

 

[kjonxx]

I've had this riding mower since 2019 and after this much use I'm anticipating replacing them even
though at this point they seem to be doing ok. From past experiences I never get more than five years
out of a Mandrel assembly. So on my last sears mower I replaced those mandrels with ones that had
grease fittings which worked real well. But---now I see from doing internet searches, all the mandrel
assemblies available for my mower are grease-less?

Could somebody please explain how these new mandrels work without grease? and is it a waste to
look for an assembly with grease fittings these days? Thanks Bob

Put your own grease fittings in before installing, I so this on alot of greaseless ones. Also notice that ones with grease fittings have rubber sealed bearings so whats the point? I usually cut a small slit in rubber seal so grease can get in on the inside. Been working for years.

 

[jd345lx188]

Couple of thoughts: Somewhere in Timken literature, the term used was "shield." This makes more sense than "seal" when grease/water/dirt can get around whatever is covering the bearing retainer.

I read Bert's post #7, just above, as the ZZ actually is a sealed bearing, as in nothing gets in or out ... ergo sealed.

However, we all just read Star Tech, post #6: "The bearings has to be change to ZZ bearings from the the 2RS bearings as the ZZ will allow grease to enter and exit the bearings while still retaining most of the grease." I read that as not "sealed."

123Bearing Co. calls the ZZs: "... 2 sheet metal deflectors, for dust-tightness. ..."

Are there no actually grease and water tight bearings available? ZZs cost more but is the difference meaningful?

RS is the designation for radial seal, which is a rubber seal and seals water/grease/dirt out (up to the point where pressure, vacuum, wear, or some other force causes the seal to fail). 2RS designates that there is one on both sides of the bearing. ZZ metal shields are not necessarily water/grease/fine dirt tight, but do keep the bigger stuff out.

I work in manufacturing, we also do some assembly. One of those assemblies calls for a 1RS bearing. The seal gets assembled on the environment (water/dirt) side, the 'no seal' side towards the grease fitting. The 1RS bearing is a special, the 2RS is readily available. We buy the 2RS bearing, pop 1 of the rubber seals out with a screwdriver or pick, and we're good to go. The 'no seal' side allows the grease to enter from the grease fitting, the seal keeps the environment stuff out and allows pressurized grease out.

I don't work in the mower world and am curious, do those of you who do work on them daily see more spindle bearing failures on the decks that have those garden hose ports built into them and used all the time?

 

[closecut]

What happens when you try to force grease into the sealed bearing is a lot of the time the inner seals are pushed into the bearing and the outer seal can actually get pushed out. The bearings has to be change to ZZ bearings from the the 2RS bearings as the ZZ will allow grease to enter and exit the bearings while still retaining most of the grease.

Also both the greaseable and non-grease spindle are the same retail price and cost.
View attachment 68671

I also see no reason to change the spindle housing when just the bearing are needing replacing; unless, you try removing the spindles to change out the bearing which leads to broken mounting screws.

A "RS" or "2RS" suffix is a rubber sealed bearing.The "2RS" is sealed on both sides.A "RS" is sealed on one side only..A shielded bearing,like with a "KD",or"KDD" bearing is a shielded bearing,It is designed to keep dirt out,but not keep grease in.A Sealed bearing does both.
The inner shield or seal can be removed by simply prying it out from the outer edge carefully with a small screwdriver.The main reason for bearing failure,according to Fafnir,the bearing company,is OVER GREASING.The grease must have room to get out of the ball path,or it will churn the grease and heat up and eventually carbonize the grease causing failure.
If you manually grease a bearing, leave some room for the grease to move out of the ball channel.I have had success drilling out the rivets of the mandrels and taking it apart,and getting access to the bearings,Replaced the rivets with cap screws and locktite. Popped out the inner seals,and left them out.Cleaned and re greased the bearings. Put Permatex#3 on mating faces of the mandrels to keep out trash.I have mandrels on an old 1986 Cub(sold by JC Penny before cub put out their own brand.)Original mandrels still working.I disassemble and put new grease in about every 5 years or so.I use a high temp grease like for wheel bearings on cars and trucks.

 

[STEVES]

OK Thanks, I might just try doing the bearing change out when the time comes and use this thread as a
reference. Other question I have is from past experience in removing the mounting bolts that hold the Mandrel
assembly in place usually break off when you try to remove them! For the normal hack mechanic
like me, that pretty much renderers the housings un-useable

I guess pre-treating the treads with penetrating oil might help that

You are removing deck, change the bearings without removing spindles the from deck. If you put on a bench it's an easy job.