Faq – About 60 Inch Lawn Mower
Ken asks…
lawn mower help!!!!!!!!!!!!!!!!!!!!?
ok so I have a 455 john deere lawn tractor i need to get a mowing deck that mulches or a kit that will that will make it mulch and the deck has to be 60 inches or my last option is getting a bagger the deck i have now is 60 inches and the tractor is a desil and cheaper the better
Staff answers:
I would keep the lawnmower running as long as you can Diesel. I don’t think you can get now.Check Blades that would mulch fine.Deere must have that option.
Maria asks…
Exmark mower….?
My husband and I are looking to purchase a new lawn mower and he is interested in the Exmark mower. We have a pretty large area to mow, therefore the 60 inch cut wouldn’t be a bad thing. It’s just a LOT of money in my opinion. Does anybody have any “pros and cons” for me about this mower?
Thank you in advance.
(I posted here in P&S because you all give the best answers.)
Staff answers:
HA! Can’t believe I spotted this.
I own a lawn care biz.
There’s a LOT of variables about just saying an Ex-Mark.
Sitting or walk-behind?
Belt driven or hydraulic drive (IF walk-behind)?
Let me post a couple of thoughts, and you may mail me for details.
For reasonably level terrain, go belt drive to save about $1000 on the unit.
The E-Z control system on walk-behinds is FABULOUS.
Choose a Kawasaki engine over a Kohler for durability.
Again, if you need details, DO write me!
George asks…
Top Speed of motorized mountain bike?
for example, a normal bicycle has wheels that are 26 inches in diameter. The “lowest” gear ratio on the bike might be a front chain wheel with 22 teeth and a rear gear having 30 teeth. That means that the gear ratio is 0.73-to-1. For each pedal stroke, the rear wheel turns 0.73 times. In other words, for each pedal stroke, the bike moves forward about 60 inches (about 3.4 mph / 5.4 kph at a 60-rpm pedaling rate). The “highest” gear ratio on the bike might be a front chain wheel with 44 teeth and a rear gear having 11 teeth. That creates a 4-to-1 gear ratio. With 26-inch wheels, the bike moves forward 326 inches with each pedal stroke. At a 120-rpm pedaling rate, the speed of the bike is 18.5 mph. now that is human power. Add in a 5 HP lawn mower engine that spins at 2000 rpms and 6pounds of tourque PSI. there thinking that wind resistance and drag the bike will not Top 50. By my calc this nike could reach 616 mph. i think it could top 150 MPH
for example, a normal bicycle has wheels that are 26 inches in diameter. The “lowest” gear ratio on the bike might be a front chain wheel with 22 teeth and a rear gear having 30 teeth. That means that the gear ratio is 0.73-to-1. For each pedal stroke, the rear wheel turns 0.73 times. In other words, for each pedal stroke, the bike moves forward about 60 inches (about 3.4 mph / 5.4 kph at a 60-rpm pedaling rate). The “highest” gear ratio on the bike might be a front chain wheel with 44 teeth and a rear gear having 11 teeth. That creates a 4-to-1 gear ratio. With 26-inch wheels, the bike moves forward 326 inches with each pedal stroke. At a 120-rpm pedaling rate, the speed of the bike is 37 mph. now that is human power. Add in a 5 HP lawn mower engine that spins at 2000 rpms and 6pounds of tourque PSI. there thinking that wind resistance and drag the bike will not Top 50. By my calc this nike could reach 616 mph. i think it could top 150 MPH
Obviuosly there are real world factors such as wind resistance tire resistance and lose of power/energy thruogh the entire mechanicle process. But that isnt that the great thing about gears and gear ratios?
In shop class 8 yrs ago we tested this theory and hit 62 mph and still had 4 gears to run through. problem was we ran out of track space on an oval track and no one was brave enough to push it farther and find out.
lawn mower engines are not geared down. they hit a certain Hp and torque at a give rpm. torque i think in this case is irrelevant . if an engine is rated at 2000 rpms and thru the gear process you are able to reach the 2000 rpm mark, then with the formula it is logical that my calcs are correct. any one with scientific data or at least something more substantial than there opinion are urged to respond. Thnx
Staff answers:
1 HP on a motorized bike will generally give 20 to 30 mph. 5 HP should get 30 to 50 mph, depending on rolling friction, drive chain efficiency and aerodynamic drag.
Your calcs are wrong because the engine doesn’t have enough torque turn the crank directly. Engines are geared down to provide more torque, and as a result loose top speed.
Be careful if you mess with this stuff; be safe and don’t get hurt.
Edit: 62 mph is most impressive, I would question the accuracy of your speed measurement. It is possible though. To get highest speeds, use racing bike with high pressure tires rather than mountain bike, use efficient drive chain, and most key, severe aerodynamics like bike racers use: low racing position, special aero helmets, etc.
Edit again: to run vehicles, engines run through a drive chain that gears the speed down and the torque up.
Power required to propel your bike = force * velocity.
Power generated by an engine is
power = torque * angular velocity.
Torque is critical because your engine won’t have enough torque to push the bike, just as you can’t push your pedals hard enough to accend a steep slope in high gear.
Final edit:
You want calcs? Cool!
Your engine puts out 6ft-lb @2000rpm.
Power = torque * omega
= 6ft*lb * 2000 * 2*pi
= 75,400 ft*lb
= 75400/33000 = 2.3HP
For comparison, a typical B&S 5 HP puts out max power at 3600 rpm:
P = 5*33000 ft*lb/min
Omega = 3600RPM * 2*pi,
T = P/omega = 7.3 ft*lb
Now gears are not the magic you think. Using gears, power is conserved (conservation of energy or 1st Law of Thermodynamics). Since power is conserved, if you use gears to speed up the output from an engine up 10x, the drive chain now has only 1/10 the torque (neglecting friction, which makes things worse).
To apply conservation of energy for a typical mountain bike, drag is about 12 lb @30mph (or 44 ft/sec):
Power = F*V = 12lb * 44 ft/sec = 528 ft*lb
divide by 550 ft*lb/sec to convert to HP:
528 ft*lb = 0.96HP required from engine, neglecting friction.
Assuming all drag is aerodynamic for simplicity, power required is proportional to V^3, so going from 30mph to 60mph requires 8x the power or 7.7HP. Drag increases by V^2, so 4x12lb = 48 lb. Doing 120 mph, 4x the 30 mph, requires 4^3 or 64x the power, or 62.4 HP, and a force of 192 lb. Using F = P/V, 5 hp or 2750ft*lb/sec / 160 mph or 235 ft/sec, = 11.7 lb. Since some 350 lb is needed to push your bike to 160, obviosly it’s not going to go that fast.
To easily do the calcs yourself, google an online bicycle calculator. An OK one is listed below, but there are many others.
Courtesy of Y!Answers