Power Take Off (crankshaft) Pulleys


The first two rows of pictures show typical PTO (Power Take Off) pullies we manufacture that allow for the attachment of a High Output Second (dual) alternator to most engine manufacturer crankshafts. It is available in twin V-belt or 8 Groove Serpentine configurations. The PTOs on the top (first) row show an optional ZRD blue finish. The picture on the middle row shows the standard (normal PTO) finish. We stock PTO pulleys that fit (bolt on to) most Yanmar engine crankshafts. For other engine manufacturers, we make the PTO on demannd. Standard delivery is 2-6 weeks.

Below the standard crankshaft PTOs (bottom - third row) are examples of three custom PTOs. The first picture is a 4 sheave PTO pulley that is designed for significantly larger engines that are able to feed multiple power take off options. This type of PTO requires additional horsepower and the availability of room around the engine in order to allow for the attachment of the options.

In the middle the photo shows how ZRD is able to custom create (special order) a PTO pulley or a new replacement pulley that will be the combination of the main (original) crankshaft pulley (one or two sheaves) plus a 2 sheave PTO. The end result is a new bolt replacement pulley for the crankshaft with three or four sheaves that will accommodate all of your needs to mount v-belts. This example was designed and manufactured to have a single 3/8" sheave to match the original crankshaft and then add two 1/2" PTO sheaves.

Pictured at the far right is an example of a customer's requirements that needed a very specific solution. It had very different specifications than is normally required of standard PTOs. Note there are multiple sheaves with different diameters and widths. The finished PTO is shown bolted on to the existing engine crankshaft pulley. Part of the PTO fits inside the crankshaft pulley with very tight tolerances. It fits like a tight leather racing glove. The crankshaft pulley and the PTO are bolted together with Titanium bolts.
 
Standard Yanmar 2 Sheave PTO - edge view     Standard Yanmar Serpentine PTO - edge view

Standard Yanmar 2 Sheave PTO - edge view

Standard Yanmar 4 sheave PTO - edge view     Very Custom 3 sheave PTO     Very Custom 2 sheave PTO

Specialized Pulleys
Depending on your situation, we may ofer to custom create (requires a special order) a new replacement pulley for most items attached to your power plant or accessories in order to have a proper total solution. The costs associated with this option varies widely depending on what is required, complexity of fabrication and the man hours that may be required. A free phone consultation is always available in order to get initial estimates for your situation.

Special Note: The following service is not provided to all manufacturers' engines. It is displayed here to show ZRD capabilities. This limitation is due to the additional side loading (mostly on water pump components) created by alternators that exceed 94 amps. This has reportedly led to premature engine failures. ZRD will provide this specific service only if authorized by the original engine manufacturer. This restriction is due to factors beyond our control that may lead to overloading and failures.

The first photo (top right) is an installation that had it's 3/8" single sheave crankshaft pulley modified to become a 1/2" single sheave version and a new 1/2" water pump pulley was made to replace it's previous 3/8" one.
  Completely Custom Refit of small Westerbeke

Westerbeke 44A before custom modifications performed
Westerbeke 44A with custom double 3-8 " pulleys, ZRD 120 amp alternator and adjustment arm  

Another example is shown in the second and third photos (bottom right - before, far right - after) of a Westerbeke 44 that was modified from a single 3/8" pulley arrangement to a double 3/8" pulley and belt design. This allowed a custom designed ZRD 120 amp alternator to be installed properly. A ZRD 140 amp solution was also possible. Again, remember in most cases, the upgrade replacement of an originally installed OEM alternator is restricted to 94 amps.

The important item of significance to note here is that the modified crankshaft pulley and the new water pump pulley were created in such a way as to ensure the alignment of the newly created sheaves with each other and the replacement alternator's sheave. This technique is applied when we design PTOs / Replace Crankshaft Pulleys for PTO attachment for ZRD Second (dual) Alternator High Output soultions. In order to ensure a proper fit, you will need to send us your existing pulley(s) and any associated & co-located hardware (washers, bolts, balancers, ...).

Special Note:
If any hardware sent to ZRD is not easily replaceable via the manufacturer or a parts supplier, ZRD must be notified in advance prior to shipment to ZRD. ZRD's only accepted liability is to a pre-arranged agreed amount ($) in the event should damage or loss of non-replaceable customer hardware occur after ZRD receipt of customer hardware and prior to customer's receipt of a completed order. The completed order shipment will contain all customer supplied hardware in addition to the ordered components. If no order is placed after ZRD receives a customer's hardware, customer agrees to assume full sole responsibility for return shipment charges and any and all liability for loss or damage. If customer does not request the return of any of his supplied hardware within thirty (30) days of receipt by ZRD, customer relinquishes all claims to supplied hardware. Under no circumstances, shall ZRD's maximum accepted liability for any loss or damaged customer hardware to ever exceed $500.


ZRD Alternator Pulleys (In Stock - Special Order)
The following ZRD stock pulleys are machined to work in conjunction with standard engine or ZRD custom PTOs to enable/ensure correct engine/alternator operation range. They are for use with large and X-large case high-output alternators with 7/8" (0.875") shaft bore. We also have an assortment of single sheave pulleys for standard shaft bore (17mm = 0.67"). Contact us for details.

Dual V, 2 - 1/2" Sheaves
Part Number: Diameter
ZP782240 2.40"
ZP782270 2.70"
ZP782300 3.00"
ZP782310 3.10"
ZP782325 3.25"
ZP782335 3.36"
ZP782350 3.53"
ZP782425 4.25"


Serpentine, 8-Groove 1.125" Width (depth)
Part Number: Diameter
ZP78S240 2.37"
ZP78S270 2.76"
ZP78S300 3.00"
ZP78S340 3.43"




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