Belt Drive Design Tension Ratios

As they operate, belt drives use span tension differentials to create a net effective pull. The two belt spans are defined as the tight side span (higher tension value) and the slack side span (lower tension value). The drive loads, as well as installation tension, impact the span tensions.

The tension ratio is defined as:

Tension Ratio = Tight Side Span Tension (lb) / Slack Side Span Tension (lb)

Based on different operating characteristics, belt drives types have different design tension ratios. Assuming 180° wrap on both pulleys, here are some typical design tension ratios:

• 4:1 for Micro-V® Belt Drives
• 5:1 for V-belt Drives
• 8:1 for Synchronous Belt Drives

Assuming other drive parameters to be equal, larger tension ratios result in lower belt pull values.  

Super HC XP (Notched Premium) Belts

Here at Gates we recently released our new patented Super HC XP high performance molded notch V-belt.  The Super HC XP belt is designed with Aramid tensile cords and a new distictive green wear-resistant backing.  This results in the Super HC XP belt being rated to transmit an average of 50% more horsepower than our standard Super HC molded notch V-belts.  This increase in capacity allows for drives that are narrower and lighter which result in less rotating mass and decreased loading on bearings and shafts.  

Currently the Super HC XP belts are only offer in 5VX cross section in both single and PowerBand construction, however, in the future other cross sections will be made available.  For further information feel free to review the Super HC XP section in our new 2015 Industrial Power Transmission catalog or contact us at PTPASupport@Gates.com or 303-744-5800.  

2015 FIRST Scholarship

The 2015 FIRST scholarship has been posted at www.Gates.com/FIRST

New Industrial Power Transmission Products Catalog

Gates has just released it's new for 2015 Industrial Power Transmission Products Catalog.

You can download your copy here:  2015 Power Transmission Products Catalog

As always, check us out at our Product Application Engineering page for more support.

Alternative Fuel Fact Sheet

Biodiesel Fuel

·       Can be pure (B100) or is often blended with petroleum based diesel.  B20 is a 20% blend of biodiesel and 80% petroleum diesel.

·       Is produced from vegetable oils (rapeseed, soybean) or animal fats reacted with alcohol to form fatty acid methyl esters.

·       Appears to be compatible with standard nitriles using standard laboratory material tests, such as room temperature immersions tests, but has a hidden danger in the field.

·       B100 permeates quickly through standard grade nitrile polymers.  The permeated fuel will attack the reinforcement layers and cover stocks which often have limited resistance to B100.

 ·       For continuous exposure all grades, Gates recommends Stallion, 

    Renegade, and Longhorn AF.  Service life could shorten with splashes of

    biodiesel on the cover.

·       For transfer or intermittent exposure to all grades biodiesel, Gates recommends Longhorn, Steer, Maverick, Brahma and Sea Horse if the hose is allowed to dry out between uses.

·       High temperature (under hood 257°F) applications accelerate the decomposition process.  Gates does not recommend using nitrile for biodiesel fuel lines above 125°F. Use 4219BG Barricade Green Shield tested to B100 up to 212°F and fuel Injection hose 4219D (FKM) tested to B100 up to 275°F.

·       B20 and below up to 125°F are compatible with 4219G and RLA. Marine Fuel Lines C5M and 4219M is recommended for B100 up to 125°F.

Ultra–Low Sulfur Diesel Fuel

·       Legislation requires a reduction of harmful emissions (less than 15ppm).

·       Sulfur is the lubricant in diesel fuel, lowering the sulfur content may drop the fuel lubricity. To achieve the new sulfur requirements, diesel manufacturers include a biodiesel (B2) additive to keep the fuel flowing smoothly and to prevent engine damage.

·       Longhorn, Longhorn AF, Steer, Maverick, Brahma, Sea Horse, and RLA are acceptable for normal transfer applications.

·       C5M, 4219D, 4219BG, 4219M and 4219G are acceptable for fuel lines.

E85 Fuels

·       85% Ethanol with 15% gasoline is not an aggressive fuel with respect to rubber compounds.

·       Any grade of nitrile rubber designed to handle refined gasoline will work with E85.

·       Longhorn, Longhorn AF, Steer, Maverick, Brahma, Sea Horse and RLA are acceptable for normal transfer applications.

·       C5M, 4219BG, 4219M and 4219G are acceptable for fuel lines.

E15 Fuels

·       15% ethanol level is more chemically aggressive, with respect to rubber materials, than 85% ethanol.

·       Very good grades of nitrile compounds – use Longhorn AF  for Petroleum Transfer

·        C5M, 4219BG and 4219D (FKM) are recommended Fuel lines.

100% Ethanol

·       Used to make E85 (85% ethanol and 15% gasoline) and E10 (10% ethanol and 90% gasoline) grades

·       Can be treated as a chemical additive and transferred with chemical hoses such as Colt (EPDM), Mustang (Gatron) or Renegade (UHMWPE) and standard grade nitrile hoses.

Hose Ends

An effective way to remember this hose selection criterion is to remember the word STAMPED.

S T A M P E D
 S = Size
 T = Temperature
A = Application
M = Material to be Conveyed
P = Pressure
E = Ends or couplings
D = Delivery (volume)

E =  Ends or Couplings

Identify end coupling to be used.

SAE couplings: North American Thread Types, JIC (37° flare), (45° flare), O-Ring Boss, O-Ring Flange, O-ring Face Seal, and SAE inverted Flare.

International standards: BSPP, BSPPT, GAZ, DIN, JIS, Komatsu (Flare 30°), Komatsu Flange Fitting and Kobelco.

The difference of the thread type is the thread configuration, seat angle, and how the coupling seals (thread interface, mating metal-seat angles and O-rings). The differences increase the possibility of mismatching threads and seats. A couplings male and female thread ends must be compatible to ensure an effective seal and prevent leaks or blow-offs.