November 30, 2009

The Tuf-Lugger Pulls Its Weight

The Tuf-Lugger cable puller is four-wheeled, maneuverable winch capable of pulling 2000lb in high gear, and up to a maximum load of 6500lb. Pulling tension will be determined by the duct geometry; while individual installations may not typically reach this force, it’s nice to have it when you need it.

The Tuf-Lugger has an on-board meter for measuring pulling tension, allowing you to monitor the load and make changes to the pull if needed. The calibrated Load Monitor System is an optional accessory to provide more accurate data (for fiber optic pulls, for example).

To increase the flexibility of the Tuf-Lugger, longer boom arms may be cut from standard Schedule 40 pipe or the Universal Extension can be used to rotate the pulling direction out of plane.

Underground: the Manhole Adapter can be used at the surface, combined with Sheaves or Quadrants anchored and hung in the vault itself. (Hanging Quadrants provide flexibility, since they can be moved and re-oriented within the vault.) A Duct Entry Guide is recommended to finally direct the cable into the duct.

Tuf-Lugger-Pulling-Cable

Keep in mind that the Tuf-Lugger is not pulling the cable itself. Lightweight pull tape is installed into the duct first, linking the cable reel at the inlet and the cable puller at the outlet. The Tuf-Lugger has open sheaves and a capstan winch to accept a variety of rope sizes (from 3/8” to 7/8” typically) – the rope is then pulled by the Tuf-Lugger, and as the rope is extracted from the duct, the cable is pulled into place.

If the calculated pulling tension is too high due to excessive length or bends in the duct, a lubricant like our Tube-Lube 326 would be recommended to mitigate the friction in the duct.

See our previous cable pulling post “A Team Effort” for even more information on the cable pulling equipment that DCD Design builds.

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November 26, 2009

Support From DCD

Sometimes a product will get lost or damaged in shipping. That doesn’t change our responsibility to our customers: to provide high-quality products and service that works for you.

“I wanted to send a note to commend the team at DCD for your efforts at supporting your products and your customers. As a distributor, Eastcom works with many different manufacturers. The product knowledge you display, and the willingness you all have at making every effort to satisfy a customer is unmatched.

We recently experienced a product damaged in shipment to the customer. First you were willing to work with me by sending me parts to try to repair the equipment at the customer’s location. The effort to repair proved too complex so you arranged for the shipment to be picked up for warranty return and repair.

This type of customer service will always lead to repeat business. It is this type of effort that many companies no longer make. However it is typical of DCD. You are all a pleasure to work with and we are proud of our association with you.

Thank you for all your efforts.

Larry
Eastcom Associates, Inc.”

Thanks for the positive comments! We try to ensure that shipments arrive intact – and we can be very hard on the couriers when they occasionally screw up! Supporting our products and our customers is a long tradition for DCD Design; it’s just the way we do things.

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November 24, 2009

Lasher Repair Facility

When it comes time to service your cable lasher, we know just the man for the job! John Innes has worked with DCD Design for four years, and was an integral part of the Cable Spinning Equipment (CSE) Company for decades prior to that.

John’s experience with overhead cable lashers and the overhead industry is second to none, and his expertise extends to all the major brands and every model you can think of!


John produced and starred in the original Lineman instruction videos.

For overhead cable lasher service and repair work – DCD, CSE or GMP – contact John.

Via email at JLInnes@sbcglobal.net
Or call 320-212-8224 (Central time)

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November 17, 2009

DCD Design Renews ISO Registration

As of November 2009, DCD Design & Manufacturing Ltd has renewed its Quality Management System to the ISO 9001:2008 standard! If you’re familiar with DCD Design, you know we’ve always built a high-quality product. You know what you’re getting and you know it’s going to work.

“Quality,” in the sense of the ISO Standard, simply defines the process: it evaluates how and why things are done, it documents how things are done, and then it records the results to show how it was done. These steps lead to consistency in a product.

In the end, small-Q quality is a result of big-Q Quality.

To attain ISO registration, everyone at DCD Design reviewed what they did, how they did it, and how they kept track of it. Then we committed to improving what we do on a continuing basis.

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November 13, 2009

Cable Pulling – A Team Effort

To continue from the previous posting, here’s some more suggestions for cable pulling. We’ve already reviewed cable tension and how to manage that. This time, I’ll cover the remainder of the hardware that can be applied to a successful pull. Starting at the beginning and progressing through the length of the pull:

- Duct Rodders are available in a range of sizes to suit the job, and are the simplest way to push or pull the initial messenger lines through the ducts.

- Duct-Checkers can be then pulled to ensure the bore is clear, and synthetic pull tape or line can be pulled through with the trailing eye.

- Attaching a pulling eye to the cable can be done with Pulling Grips or with DCD’s Power-Grip Pulling Eyes. Pulling Grips are very common, but you must make allowance for Safety Factors between the pulling force and the breaking strength. DCD’s Power-Grips are re-useable end fittings that are stronger than the cable, and they limit damage to the cable to a very short end section.

- A Line Swivel should be linked between the pulling cable and the cable’s pulling eye to eliminate twist in the electrical cable. Eliminating this torque also contributes to reduced pulling force. Always choose a Line Swivel with excess capacity.

- At the cable reel end, a Duct Entry Guide provides a durable roller at the duct entry. DCD Guides are provided with a standard spray nozzle for connecting to a Lubricant Applicator to provide continuous cable lubrication.

- Exiting the duct at the pulling end, DCD Quadrants have large aluminum rollers to maximize corner radius and distribute point loads on the cable. Alternatively, the range of DCD Hanger Sheaves offers a range of sheave radii to suit the cable manufacturers’ design allowables.

- An Offset-Eye Pulling Grip can be laced onto the mid-span of the cable for short, repetitive pulls to draw extra cable at the pulling end.

- Finally, the Tuf-Lugger does the heavy lifting – as described before.

Individually, each offers some small advantage when pulling cable. And altogether, you’ve got a pretty good team!

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November 10, 2009

Lest We Forget

And to mark Remembrance Day (Veterans’ Day in the US), let’s give some thought to our friends and family members who are or who have served in the armed forces. Thanks, Grandpa Ed.

remembrance-poppy

The production offices of DCD Design will be closed on November 11th to observe Remembrance Day. However, Ryan will be manning the Sales Desk to respond to your inquiries. Call in to wish him well!

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Cable Pulling – Some General Recommendations

We were asked for some advice on a 1500MCM electrical cable being installed last week. It wasn’t a long pull but the pulling tension was higher than expected, and the cable jacket was experiencing some damage coming out of the vault. Overall, there wasn’t anything wrong but we suggested a few incremental changes to reduce the pulling tension.

Cables have design allowables from the factory: minimum bend radius and sidewall bearing pressure are the concern here. Minimum bend radius is self-explanatory: try to bend a cable too hard, and it will ‘kink’ – at the least, the outside layers will risk delaminating. Minimum bend radius will define the sheave or quadrant that must be used when turning corners under tension.

Sidewall bearing pressure is similar, but it relates the pulling tension to the bend radius. This limit can be even more restrictive, and knowing your cable specifications are a necessity when designing your pull.

Sidewall bearing pressure is measured in pounds per feet: you can allow more tension (pounds) only if you have a larger radius (feet). If a single sheave isn’t big enough, then an assembly of sheaves or a quadrant become necessary.

Gentle bends maybe acceptable for a cable, but a 90 degree underground sweep at the end of the pull – where the tension is greatest – could damage the jacket or insulation without your knowledge.

Since the length and geometry of the pull cannot be changed in most cases, the remaining option is to reduce the pulling tension. DCD Design has the Tube-Lube 326 sprayable lubricant that thoroughly wets the cable jacket and reduces friction with less mess, reduced consumption, and no environmental concerns. And all our Manhole Tools have quick-connect spray outlets built-in for easy application.

Reducing tension will allow more freedom for directing the cable at the pulling end. A cable puller like DCD’s Tuf-Lugger has an on-board meter for measuring pulling tension, allowing you to monitor the load and make changes to the pull if needed. The calibrated Load Monitor System is an optional accessory to provide more accurate data (for fiber optic pulls, for example) but it’s not typically required for electrical cable.

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November 4, 2009

Understanding Blower Performance

Here’s a quick explanation of flow rate versus pressure. When you need to go farther, make sure you’re comparing the right numbers!

The output of a blower is usually specified in terms of (i) its flow rate (cfm), and (ii) its pressure (psi). The flow rate determines how fast the blower can move a projectile, and the pressure determines how much and how far the projectile can pull a load. (Compare it with RPM vs. Torque.)

When a blower is running with an unrestricted outlet, it will produce its maximum specified flow rate because there is no resistance against it. (The RPM’s go to red-line.)

If the blower is attached to a length of empty conduit, the blower has to move all the air in the conduit to push any through. Friction against the conduit wall will resist that movement. As the blower works against this backpressure, its flow rate drops. (Pop the clutch and engage the drivetrain, the RPM’s drop.)

Therefore … a blower can never produce its maximum specified flow rate in a practical application due to air friction in the duct.

As the length of conduit increases, friction increases, backpressure increases, and flow rate decreases. At some point, the backpressure will increase to a point at which it equals the maximum pressure that the blower can generate, and the flow rate will be zero. (Drop the RPM’s against Torque, and the engine will stall.)

When a projectile is inserted, it blocks the conduit. As more air is pushed in behind the projectile, the backpressure rises until it exceeds the projectile’s drag and it begins to move along the conduit. Therefore … the drag creates the backpressure which, in turn, determines the blower flow rate and ultimately the speed of the projectile. (Keep your foot down, and the RPM’s up, and you’ll overcome Torque and accelerate.)

As the projectile moves down the conduit, the drag force increases because of the weight and friction of the line being pulled is increasing. At some distance, the increasing backpressure equals the maximum pressure that the blower can develop, and the projectile will stall. (Think tractor pulls: the towing load is always increasing; RPM’s are limited; sooner or later, the tractor gets stuck.)

Because only blowing pressure can overcome backpressure, a blower with higher blowing pressure capability will ultimately go farther. The DCD Power Blower was designed around twin, high-pressure motors to go farther. Compare the data when you have a line-blowing job. More pressure, more distance.

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