Constant Velocity: definition
Correct Sizing of a CV shaft
  CV UJ guide




An excellent article on CV PTOs by the Government of Alberta




New CV Technology:


The Thompson Coupling (video)



Cornay Company







Order a Constant Velocity PTOs @























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Greasing links:



Weasler CV Greasing doc



Walterscheid Powerdrive



Bondioli & Pavesi SFT








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Constant Velocity Agricultural PTO Shafts

80 degree Walterscheid




(to replace Weasler CV)




information and site sponcered by



There are only three major Original Equipment Manufacturers (OEM) of constant velocity power take off drivelines.


All of the other CV manufacturers have copied one of the originals in some way or another. Granted, they have paid attention to quality control, but their aim has always been to enter the market place and compete using price as their only weapon. Thus, it is our opinion that they are inferior products by their very nature.


The key word in the OEM acronym is "Original". This means there is an entire engineering department behind the design, the choice of materials and the tolerances adhered to. It means they are constantly field testing and lab testing the product. It means they are tracking its application and studying its performance. And here's the bad news: It means they are re-engineering too, making new parts to replace the old; new, improved designs, different dimensions, different versions, different parts. In some ways, manufacturing has become way too easy!


The "knock off" brands can only copy the older versions whose patent has expired or make subtle changes to the copied product in order to beat the patent law.


Statistically speaking, the knock offs come into the market slightly cheaper, but have an operational life one half of the OEMs. In our opinion, there is no comparison when you study dollars to hours of use. The OEM shaft gets cheaper by the minute.




The three major OEM manufacturers of constant velocity PTOs are:



Bondioli & Pavesi




Weasler Manufacturing




In our opinion, life cycle is everything. Besides the obvious long term cost savings, consider your down time and your maintenance costs. Where knock off brands brag about 1,000 hours of life, we have had customers who get 2,400 hours of service life with a properly sized and properly maintained CV.




It is extremely important that the PTO shaft be sized correctly for maximum life. Often times, we see implements using a shaft that is just barely adequate insofar as size is concerned. By sizing these marginal applications up, you will indeed gain more hours of use.


Always consider the application. An implement being run for 12 hours a day, 7 days a week obviously needs more attention than an implement that is only used for 4 hours every month. The greater the operating angle, the more maintanence your cv will need. A continuous duty 50 HP application needs more driveline than an intermittent 50 HP application. A 50 HP driveline will transmit 100 HP if needed, but it won't last very long in that range.


Lastly, there primarily 2 types of agricultural CVs. Generally speaking, 80 degree CVs are designed to be fitted from tractor to implement for use where there is semi-constant articulation (changing angles). 50 degree CVs are designed for a static application (non-changing angle).



The following chart should be helpful:(popular 80 degree only)     < detail UJ guide >

note: most CV U joints are not symmetrical


Series Manufacturer

UJ dimension (mm)

HP @ 540 RPM HP @ 1000 RPM
2280 Walterscheid 24x61 / 22x76
14 Series Weasler 28.6x66.6 / 28.6x108
Size 4 Bondioli & Pavesi 22x86
2380 Walterscheid 27x74.5 / 24x91
2480 Walterscheid 32x76 / 27x94
35 Series Weasler 31.8x81.3 / 31.8x109.2
Size 6 Bondioli & Pavesi 27x100
2580 Walterscheid 36x89 / 32x106
Size 8 Bondioli & Pavesi 30.2x106
55 Series Weasler 38.9x94.5 / 33.3x110.7
Size SO Bondioli & Pavesi  



Notice that the U joint dimensions above do not correspond logically to the horse power ratings. From experience, I can also say that the comparative values from the manufacturers do not jive with what we know based on what we see coming out of the field. Indeed, if you study horse power charts the one consistency is the inconsistancy chart after chart, year after year. But we are NOT engineers, so let's just trust the numbers.




The 'old standard' rule for greasing constant velocity drivelines is every 8 hours of use. Any grease that will hold a high temperature without breaking down will suffice. Greasing the u joints is not nearly as important as greasing the ball joint. Time after time we have seen perfectly good u joints hanging from a destroyed ball. The ball joint is the key to the CV working, and it is most definitely the weak point.


New products by all three manufacturers have extended the greasing interval to varying degrees. This has been achieved mostly through using tighter seals and more sophisticated shielding. You can read the specifications yourself (see links to left), but old fashioned common sense is still the best procedure. Consider the nature of the application. Dirt and debri create friction which creates heat which destroys moving parts. The cleaner and cooler you can keep your moving parts, the longer they will last. PERIOD.





Nothing will protect you expensive constant velocity driveline like a well maintained shield. They call them safety shields, but they will not keep you safe from a rotating driveline. Nothing will. They will, however, keep your moving parts protected from debri, which will increase the lifespan of your driveline.


Safety shield have grease zerks too, usually plastic ones. Your shield rides on a plastic bearing that allows the shield to rotate independently of the driveline. A few shots of grease will keep the plastic shield bearing from burning up.


Constant velocity shields are expensive as well as required by OSHA. Nevertheless, we advise replacing the shield as soon as it incurs damage or excessive wear. It can save you money in the long run.





Because the constant velocity PTO is a sophisticated piece of mechanical engineering, in most cases the entire PTO driveline should be replaced. There are rare instances where only universal joints are worn or a single yoke can be changed to bring the assembly back to a usable condition. However this is a rare instance and should only be judged by a qualified, experienced driveline mechanic. Nothing is more painful than spending good money in a failed experiment.


Always consider the life cycle. If your CV PTO driveline has given you 2,000 hours of life, you have got your money's worth. Gambling on a partial repair could easily result in additional expense to the related parts on either side of the driveline.


Since the constant velocity joint itself is the weak link in your PTO, many users replace only the CV half of the driveline. This will work fine provided the rear half is still in good working condition and will not fail before the new CV joint does. If for instance, the implement connecting universal joint siezes soon after a new CV half shaft is installed, the resulting vibration and binding will most likely destroy the CV joint in a matter of hours.








Old 70 degree CV Obsolete
50 degree CV




80 degree CV





Power Drive

click to enlarge




The Power Drive series has several engineering advantages both in increased ball surface area and lubrication, however we have observed a slight reduction in the turning radius of P580 vs 2580. The universal joint dimensions in the two are identical, but due to the reconfigured ball and socket design, interferance occures prior to 80 degrees (our observation only). Other than that, the Power Drive series should extend life under normal conditions and proper maintenance.





Bondioli and Pavesi:


Old 70 degree CV   Obsolete
Old 80 degree CV   Obsolete
650 series CV
size 6 link        size 8 link
03 ? Series CV   Obsolete
50 degree EL CV

Size 4

Size 6

80 degree EL CV

Size 4

Size 6

Size 8

Size SO


Bondioli & Pavesi EL CV (Extended Life) claims a 50 hour greasing interval. While we are impressed by the new design features and believe this shaft will outlast the previous designs, we are recommending caution. 50 hours is a long time! Try testing at 30 hours and lengthen the interval if possible based on a close inspection.


What we like about this CV is the X-tra large ball. BYP dramatically increased the critical surface area by enlarging the ball; and at the same time discovered that a smaller, lighter U joint would carry the necessary torque. Thus they have matched ball size to UJ size in terms of torque capacity. The decrease in mass is extremely helpful in limiting overall wear and extending life. We have actually seen cases where the U joint failed before the ball, resulting in an inexpensive repair!







Weasler Manufacturing :


50 degree CV

click to enlarge






80 degree CV

click to enlarge








80 degree CV  


Weasler has had great success with their unique CV ball design. Rather than a double socket in the center yoke, you can see that they use machined pins, which fit into balls located in the two outer yokes. The other significant difference between Weasler and the European designs is the telescoping shaft. Weasler uses a solid splined shaft that mates to a splined sleeve, whereas BYP and Walterscheid use their respective profile tubes.


Splined shafting increases the mass but is very durable. In our opinion, this gives the Weasler shaft an advantage in short span applications and as the distance between tractor and implement increases it becomes more and more a liability (comparatively).





There are two levels of distribution for constant velocity drivelines as well as similar equipment. On the OEM level, CV PTO manufacturers sell to John Deer, Case, New Holland, etc. in addition to smaller manufacturers of agricultural implements. The engineering department (s) will determine the proper shaft for the application and equip each individual implement with its own shaft. Once the life cycle of the PTO shaft is reached, the end user must find a source for replacement.


On the after-market level, implement dealers may stock assemblies for the implements they sell. Additionally, there are numerous distributors who specialize in drivelines such as ourselves, Drive Line Service of Fresno.


We have been repairing, replacing and retrofitting constant velocity assemblies for 20 years.



** Some products, such as the Weasler 55 series 50 degree CV, are available only through the implement manufacturers who use the product. This arrangement is termed "proprietary" and is specific on a case by case basis. Implement connection yokes, including clutches, often times fall under this 'proprietary" catagory. In our opinion, all such arrangements do a dis-service to the end user because the supply of replacement parts is often times inadequate to the demand.







Assuming your shaft is correctly sized in the first place, replacing any OEM shaft with another OEM shaft of comparable size should not create any difficulty.