INSTALLATION
The following installation instruction and service data is for Pitts direct shaft driven and belt driven electromagnetic clutches. Proper assembly, installation, and maintenance will assure optimal application performance and extended life. Please read the appropriate section prior to assembly and operation.
- If the power driving source, such as vehicle engine, electric motor, etc. has not been equipped with a mounting platform, extended bumper or suitable frame work to support the pump/clutch assembly, this must be fabricated first. Most any method is acceptable as long as the platform will adequately support the total weight of the pump/clutch/bracket assembly. The mounting platform must also allow for close tolerance adjustment and alignment of the clutch center line to the power source shaft center line. This alignment must be within 3°. Check clutch and bracket dimension prior
to fabrication of platform. - Mount the Pitts Clutch to the appropriate Pitts foot mount bracket with the bolts provided and torque to specified limits.
- Loosely position the clutch/bracket assembly on the previously fabricated mounting platform. (NOTE: Remember that close alignment is very important – if necessary, use suitable shims between the bracket and mounting platform. An alignment of zero degrees (0°) vertically and horizontally between clutch and power source shaft center line is optimum. Do not exceed 3°.
- Drill required holes in platform to correspond to the foot mount bracket on the clutch.
- Loosely install, mount bracket bolts, nuts, lock washers. Re-check alignment (per item3), and secure all bolts. Torque to specified limits.
- Remove alignment tools and/or other devices used.
- Mount pump to foot bracket on opposite side from clutch. (NOTE: Lubrication and cleanliness of the pump shaft and clutch bore is important. Thoroughly clean these areas of any contamination. Apply a thin coating of molybdenum disulfide grease on the shaft and in the bore. This will avoid instaliation interference, resist corrosion, and reduce friction wear). Use mounting bolts long enough to engage at least three-fourths of the threads in the mounting bracket. Do not use bolts that will touch the clutch housing after tightening. Always use lock washers. Clutches with keyways are provided with two dorman plugs. Wh’en a, short shaft hydraulic pump is used, the smaller plug should be tapped into the clutch bore until it bottoms on the pump shaft. If a long shaft hydraulic pump is used, then the larger plug should be installed the same way. (NOTE: it is important to install the dorman plug(s). This keeps contamination out and prevents the shaft key from moving outward.
- Measure and select an appropriate sized universal drive line. (NOTE: consult with drive line manufacturers specifications and select a drive line that is adequately sized to accommodate the pump and overall application requirements.) See additional notes on each clutch model page in Pitts clutch catalog.
- Install drive line between clutch and power source. Install bolts, nuts and lock washers. Torque to specified limits. (NOTE: inspect the arive line for proper phasing. This means the flange yoke ears on each end of the shaft must be directly in line. If not, remove and disassemble the sh”ft at the splined connection and align the flange yoke ears.)
- If a speed control device is to be used, install per manufacturer’s instructions.
- This portion of the assembly is now complete. Proceed to final installation.
- Assemble the clutch, pump and bracket using bolts that will not bottom on the clutch housing. (NOTE: Lubrication and cleanliness of the pump shaft and clutch bore is important. Thoroughly clean these areas of any contamination. Apply a thin coating of molybdenum disulfide grease on the shaft and in the bore. This will avoid installation interference, resist corrosion and reduce friction wear). Clutches with keyways are provided with two dorman plugs. When a short shaft hydraulic pump is used, the smaller plug should be tapped into the clutch bore until it bottoms out on the pump shaft. If a long shaft hydraulic pump is used, then the larger plug should be installed the same way.
- Mounting the pump/clutch/bracket assembly may be accomplished by various methods. You may find that on some vehicle engines there are existing available brackets and/or engine location points whereby a simple fabricated bracket will allow mounting the pump/clutch/bracket assembly with ease. Others may require a more elaborate method to mount the assembly. An alternative to fabricating your own engine mounting bracket is to use a commercially available, air-conditioning mount and drive kit. These kits may be purchased from most auto and truck air conditioning warehouse supply centers in your area.
- With a suitable mount/drive bracket in place and all necessary minor adjustments completed, you are now ready to install the pump/clutch/bracket assembly. Make sure that the pulleys are lined up and the shafts are parallel. This can be done by placing a straight edge against the outside edge of the driver pulley and clutch pulley and moving clutch/pump/bracket until the straight edge touches two sides of both pulleys. Use extreme caution and avoid any possible interference with other accessory members and drive belts. Stay clear of the radiator, fan, and hood area. Misalignment causes many problems, some of which are:
- STABILITY: Misaligned belts are subject to turnover or rolloff.
- NOISE: Misaligned belts can create a noisy drive.
- WEAR: Misalignment will accelerate wear on the side of the belt that comes in contact with tbe pulley first.
- LIFE: A significant degree of misalignment rapidly decreases belt life.
- MULTIPLE BELT DRIVE: When necessary to use more than one belt on a drive, use a matched set of belts. If all of the belts are not of the same length, the shorter belt will operate under more tension than the longer one and their service life may be correspondingly shortened. Therefore, if a drive is designed to use more than one belt, order the belts in matched sets. Make sure the matched set is of belts from the same manufacturer. If belts of different manufacturers are used, the pitch line location and other construction features will not be the same. This will result in the belts not operating property together.
- Position the assembly so that the belts can be put on without force. Although V-Belts are elastic, they are not rubber bands. Forcing a belt over the groove can result in broken tensil cords in the belt and limited belt life. Using a belt tension meter, tighten belts to 100-110 lbs., per strand.
- Completely inspect the entire assembly and installation. Check and secure all areas for loose or removed components during the installation.
- Proper connection of the clutch coil to the D.C. Electrical System is very important. Locate a circuit controlled by the vehicle ignition
switch, if possible. This will prevent the clutch from being engaged when the vehicle is not in use. The coil in the field assembly is continuous run wire. One end of the wire is connected to positive (+). The other end to negative (-) (ground). If the coil has only one lead wire protruding from the housing, it will be connected to positive (+) as the other end is internally grounded to the case. If two lead wires are protruding, connect one to positive (+) and one to negative (-) (ground). Proper clutch operation and clutch life relies on an adequate supply of rated D.C. voltage to the field coil. LOW VOLTAGE = CLUTCH FAILURE The wiring circuit may vary, depending upon whether or not a speed control device is used in the system. This schematic illustrates a simple method of connecting the D.C circuitry. - Important: When the system installation is complete, mechanically and electrically, and the pump/clutch can be operated, a functional
check is necessary. With the power source running at 1,000 to 1,200 RPM, cycle the clutch on/off at a rate of 5 sec. on 5 sec. off for a total of 25 cycles. The armature plate should “Snap” firmly against the rotor. If not, re-check for rated voltage at the lead wire and check for proper grounding. - The Pitts Clutch automatically compensates for wear requiring no adjustment throughout the life of the clutch. DO NOT lubricate the unit. If the clutch should fail to operate, check the electric circuit to be sure that the proper voltage is being supplied to the clutch. DO NOT attempt to make any mechanical adjustments on the clutch.
- CAUTION: At the moment of engagement, the clutch must pickup all related inertia load of the clutch components and other components being put into rotary motion. This action is correlated to dynamic torque. The larger the clutch and related components the higher the inertia load. High R.P.M. engagement of the clutch creates an excessive shock load and may cause breakage of the leaf springs and/or clutch slippage and ultimate clutch failure. On direct drive clutches the input drive shaft may also break causing excessive damage to surrounding area. Please refer to these recommendations regarding maximum clutch engagement R.P.M.
| Clutch Model | H24 | H27 | H28 | H36 | H49 | H55 |
| Max. engagement R.P.M. | 2,500 | 1,800 | 1,500 | 1,200 | 1,200 | 1,200 |
CONCLUSION:
Satisfactory performance and life expectance of your clutch drive system depends on:
- MATCHED COMPONENTS: Pump/Clutch/Brackets and Drive Line equally sized to handle the job.
- ALIGNMENT: Direct Drive Lines within 30 (00 is optimum). Belt Drives within 1/8″ (Pulley to Pulley).
- NO LEAKS: Hydraulic Fluid, oil and contamination in and around clutch friction surfaces and bearings equals “Short Life”.
- ELECTRICAL: Full rated D.C. voltage must be applied to coil. A loss of 1 volt, on a 12 volt system, equals 90/0 less torque.
- SCHEDULED MAINTENANCE: Inspect the entire drive system periodically for proper operation.
- HIGH RPM ENGAGEMENT: Refer to item 5 (above). Use caution signs – train the operator.