Setting Application Rates For Hydraulically Driven Pumps
CAUTION: While these calculations will
give you a good approximation of the required pump speed, tractor wheel
slippage will affect rates. An actual field check of application rate is
recommended, particularly if a very precise rate is desired.
CAUTION: Check your tractor manufacturer's
recommendations on continuous use of hydraulic motors.
The following calculations provide the desired speed for precise application
rates:
1. (Width of Machine [Feet]) (Tractor speed [Mph]) DIV 16.5 x 2 = Acres Per Hour 2. (Desired Rate Gallons [gallons per acre]) x (Acres Per Hour) = Gallons Per Hour 3. (Gallons Per Hour DIV 60 [minutes]) x (128 [oz. per gallon]) = Ounces Per Min. 4. For 5/8-inch tubes: Number of Tubes x 1.6 = Ounces Per Revolution For 3/8-inch tubes: Number of Tubes x .8 = Ounces Per Revolution 5. (Ounces Per Minute DIV Ounces Per Revolution) = Pump rpm |
Now, with the engine running at fast idle and the hydraulic lever in
the "on" position, adjust the variable speed control on the pump
drive to achieve the desired revolutions per minute. That's all there is
to it.
EXAMPLE: Width of machine = 21 feet Application rate desired = 12 gallons per acre Tractor speed = 5 miles per hour Tube size = 5/8 inch Number of tubes = 9 1. (21 x 2 x 5) DIV 16.5 = 12.73 acres per hour 2. 12 x 12.73 = 152.76 gallons per hour 3. (152.76 DIV 60) x 128 = 326.40 ounces per minute 4. 9 x 1.6 = 14.4 ounces per revolution 5. (326.40 DIV 14.4) = 22.6 revolutions per minute |
PUMP SPEED MUST NOT EXCEED 65 RPM
Once you've selected sprocket sizes, use the following formula
to make sure. If pump rpm works out to more than 65 rpm, choose different
sprocket sizes and work through the formulas again.
With chain on center cluster sprockets: Pump RPM = ((M) (A) 336) DIV ((B) (C))
M = Speed, mph
A = Teeth on ground wheel sprocket
B = Ground wheel diameter, inches
C = Teeth on jackshaft sprocket
With chain on other than center cluster sprockets:
Pump Speed = RPM calculated above x (Teeth on Jackshaft Cluster Sprocket DIV Teeth on Pumpshaft Cluster Sprocket)
The rightmost part of each formula below is the ratio of all intermediate "driving sprockets" (J, M, O, etc) to all intermediate "driven sprockets" ( K, L, P, etc.).
Using the appropriate formula from below, find the combined ratio on the right-hand side. Then assume a convenient size for either "A" or "C" and solve for the number of teeth on the other sprocket.
For Model L Pumps
(A DIV C) = (Gallons Per Acre x D x B) DIV 25,000 x (K x L x P DIV J x M x O)
For Model B Pumps
A DIV C = (Gallons Per Acre x D x B) DIV 12,442 X (K x L x P) DIV (J
x M x O)
Multisprocket drive, pump jackshaft (C) driven from implement jackshaft
by sprocket (J).