Crank Counterweight on Cub 22 Mower

[Paul in NJ]

Hello

Is there a difference in the counterweighted crank arm between the 4.5 ft. and 5 ft. sickle bar Cub 22 mowers ?

Paul in NJ

[welderrx]

Hey Paul it should be the same the length of stroke doesn't change, they just have more blades and guards on a longer cutter bar. TJ

[Paul in NJ]

TJ, thanks for the reply.

I keep thinking that since the knife is 6" longer on the 5 foot mower version, there would be additional weight added to the counterweight to provide balance for the additional weight of the 5 ft knife over the 4.5 ft knife.

[halftonstude]

The counterweight isn't for length of the stroke, it's for mass of what is being moved back and forth. However, the speed of rotation plays with counterweights as well. I was a steam locomotive fireman for 5 years on three different steam locomotives, and spent a considerable amount of my spare time reading and learning about steam locomotive design and construction - primarily due to a problem with the New York, New Haven, and Hartford's giant I-5 passenger locomotives. Though the top speed along the Northeast Corridor was 88 mph, the engineers were complaining about wheel hop at speeds over 100. The counterweights on the driver wheels were causing the wheels to lift off the rail at excessive speeds. The counterweight has to have some component corresponding with the mass of the reciprocating parts (for the 22 mower that would be the knife, pitman, and attaching components like the fork and straps) but also the speed at which the parts are reciprocating. Centrifugal forces change with rotational speeds, and therefore the mass of the counterweight plus the force at which the weight is being slung around the flywheel shaft will change with speed: the mass won't change, but the force will change with speed. So, as far as steam locomotives are concerned, there was always a bit of overbalance, however, since the overbalance rotational force increases with the square of the velocity, and is undesirable, the attempt to even out the vertical unbalance with that of the horizontal unbalance (same problems with our little mowers) is always a trade off when the speed is changed from actual design speed. horizontal unbalance is when the counterweight is at the extreme ends of travel of the knife, whereas vertical unbalance is when the counterweights are at the top or bottom of the flywheel position. This doesn't even get into the resonant vibration frequency of the remainder of the tractor to which the mower is rigidly attached. Springs and shocks (first order and second order differential components) can calm the magnitude of the vibrations, used on automobiles to make the ride more comfortable. Boy i rambled there, sorry.... Doesn't quite answer the question about there being a different counterweight for the different sized knives, however, knowing much of the math behind counterweight design, and the fact that these mowers will never be used at the exact speed for which they were designed (is anybody's governor perfect?) i'd think it would be unlikely there would be different counterweights for such a small change in mass. Parts book shows only one part number for the flywheel with wrist pin and nut assembly...
c

[Nelson 634]

I love knowing how and why stuff works. I enjoyed the read. Explains a lot that I see and feel on my cub sickle bar mower. I never thought about the tractor mass, as well as connection points and tires as somewhat of a dampening device. Again I enjoyed the read. Thank you.

[welderrx]

Stude your right about the Loco's I was a machinist for 3 1/2 years and have been lead Repairman/Foreman in the Track Dept of a class one RR for 16 1/2 years maintaining Loco Cranes & all the other equipment they use, but a sickle bar isn't nearly so precise it's really counterweighted for torque for inertia for when you get into a heavy thick stand. My Uncle cut thousands of acres over the years with his IH C-32 tow behind right up till he passed away. I have it now and it's funny at certain RPM's it just about hops off the ground when its getting up to speed. I really enjoyed watching UP get their Big Boy back on the rails, hopefully it comes East. TJ

[halftonstude]

Thanks for reminding me I'll probably never see 4014 running... curves out east are way too short and we don't have wye's or turntables big enough to turn that behemoth. I saw it static along with half of the other static displays. You're exactly right with this mower, some of the counterweight (probably overweight) is for momentum because when the weight is at the maximum torque position (1/4 way around) the blades are half way between the rock guards or ledgers. Now is the chicken or the egg question... is the counterweight for torque or balance? I'd guess balance first, then they designed the travel to make use of the available rotational inertia that had developed at that point. Can you imagine that amount of mass flopping back and forth with NO counterbalance? I just came from the rodeo here, that cub wouldn't be able to hold a candle to a bucking bronco!

Just about hops off the ground, are you telling me you're experiencing wheel hop like the NH I-5's? LOL!

[Paul in NJ]

This answers my primary question where IH has used the same counterweight design on both the 4.5 and 5 foot mowers. I am rebuilding this C22 mower and down to two items. I have some knife knock that is traced down to worn guides at the base of the mower where the knife head is guided. The other is some clatter in the back end which is either backlash in the PTO drive or the rear bushing of the mower drive is worn. Both of these items I am checking into. The mower has more vibration than I recall from past experience. My last Cub was a 1949 with an era correct C22 mower. Mower back then has very low wear and I don't recall seeing as much vibration as I have with my current mower.

[welderrx]

Hey Paul , I helped a buddy about 15 years ago with a similar problem on a New Idea mower we milled a little bit off the mounting faces of the guides by the inner shoe and tightened it up some, it worked great until he caught a steel post trying to mow under the bottom strand of the electric fence and broke something in the gear box. Its a fine line between to loose and to tight you want it loose enough so it doesn't bind but not loose enough that the blades are to far away from the guides or it wont cut well or plugs easily. both of my IH mowers have the ball bearing end on the pitman arm you might have to re-bush yours if its to sloppy. Spray it down with some lube as well so it isn't running dry until it gets the grass juices on it that will help. Even a perfectly set up mower can look like it wants to grenade itself it'll quiet down one it gets some grass in it. TJ

[halftonstude]

is this a new lubricant i need to put on my shelf? Grass juice? is it available at TSC or Agri-Supply? I already have 4 oil cans behind my lathe for the various bits there (way oil, spindle oil, high pressure grease, electric motor oil, cutting oil...), as well as multiple shelves for the vehicles (finally found ONE oil that will work in 4 of my cars...), 80W-90, 90W-135, SAE 30, SAE 20, 10W-30, 10W-40... i'm running out of room!

[tmays]

is this a new lubricant i need to put on my shelf? Grass juice? is it available at TSC or Agri-Supply? I already have 4 oil cans behind my lathe for the various bits there (way oil, spindle oil, high pressure grease, electric motor oil, cutting oil...), as well as multiple shelves for the vehicles (finally found ONE oil that will work in 4 of my cars...), 80W-90, 90W-135, SAE 30, SAE 20, 10W-30, 10W-40... i'm running out of room!

Lol. You jest, but it’s right there in the manual. So stock up! Lol

[welderrx]

Well right now you still need a prescription in NJ for that, but then your not supposed to operate machinery

[Don McCombs]

In Colorado, it’s available over the counter.

[Cubfriend]

Could any of this discussion be related to the diameter of the rear pulley? One being 4” and the later one being 4.5”.

[Jim Becker]

The 5' cutter bar was available at least by 1952. The 4.5' could be ordered at least until 1958. It could have been longer either way. That is the biggest range I can document. During all those years that both were available, all that changed for the particular mower was the cutter bar. In fact, some of the time the mower was shipped with no cutter bar and the cutter bar was supplied as a completing package. The pulley changed in 1955, had no connection to bar length.