timber hitch – SCOUT PIONEERING

Making a Trestle

Lashing together a Trestle from Bamboo Spars (note the friction tape)

The following text is by Adolph E. Peschke as presented in the 1998 printing of the 1993 edition of the Pioneering Merit Badge Pamphlet:

A trestle is the basic component for building a bridge in a pioneering project. It is used to support the walkways.

The most basic form of a trestle is an H-frame. It consists of two legs, two ledgers, and two cross braces (see figure 125). When building a bridge, the top ledger is also called a transom. This is the part that supports the walkways.

To make an H-frame trestle, the two ledgers are lashed near the top and bottom of the legs and the cross braces are added, lashing them to the legs.

All of the lashing on the H-frame trestle is done with two types of lashings: a square lashing and a diagonal lashing. The ledgers are lashed to the legs with square lashings. Although it might not look like it, the cross braces are also lashed to the legs with square lashings, not a diagonal lashing. A diagonal lashing is used to lash the two cross braces together where they cross in the center.

When setting out to build an H-frame trestle, choose the two spars for legs first. These spars can be most any length, depending on the type and height of the structure you’re building.

To build a basic H-frame, lay the two legs on the ground with the two butt ends of the spars at the same end and even with each other. Then add the ledgers.

Ledgers. The ledgers are spars that are typically 2 to 2-1/2 inches in diameter. They are lashed to the legs with square lashings. Any of the three square lashings (shown in this pamphlet) can be used. The position of the ledgers on the legs will depend on the structure you’re building. There are a couple of general rules to keep in mind.

Assembling the X-Brace Side — This Trestle is One of Several Subassemblies in a Larger Project

First, always keep the legs parallel and the butt ends of the legs even with each other as you’re lashing on the ledgers.* If you don’t, the trestle will stand crooked when you stand it up. As you add the ledgers, they should not stick out too far beyond the legs. You must leave enough room at the ends to tie the lashing, Any more will get in the way.

When using a Traditional Square Lashing or a Modified Square Lashing to tie the ledgers to the legs, be sure the starting clove hitch is placed on the leg so it’s beneath the ledger. When the clove hitch is below the ledger it will support it when the trestle is stood upright. As you tie the lashings, make sure they ar all very tight.

If you use a Japanese Mark II Square Lashing, you can start this lashing with a clove hitch in the middle of the rope to help support the ledger.

Cross braces. Next, the cross braces are added. The cross braces are spars that are usually 2 inches in diameter. They are lashed to the legs in a particular sequence.

First, flip the trestle over and work on the opposite side from the ledgers (see figure 125). Lash one cross brace to the back side of both legs. As mentioned before, use a square lashing (not a diagonal lashing) to attach the ends of the cross braces to the legs.

The second cross brace is added so that the bottom end is on the same side as both ends of the first cross brace. The other end is placed on the front side, the side with the ledgers (see figure 125). This is done so that the cross braces are standing slightly apart. There will be a gap where they cross at the center.

Trestle built with 5' Scout Staves — Trestle built with 5′ Scout Staves

Diagonal Lashing. After the ends of the ledgers and the cross braces are lashed to the legs, stand the trestle up on end. Adjust the trestle so that the legs are parallel. Also check to see that the top ledger is parallel to the ground. If it is not, lower the trestle, untie the lashing, and adjust it.

When the legs are parallel and the top ledger is parallel to the ground, you’re ready to tie the diagonal lashing to the cross braces while the trestle is standing upright. This lashing is very important to the strength of the trestle.

The diagonal lashing creates triangles that are important to stiffen the arrangement of the spars and to keep the trestle from racking. Look around at steel towers, bridges, or buildings being erected and you will see the triangle used in many places for the same reasons as we use it to build a trestle.

When the cross braces are lashed to the legs, there is a slight gap between them where they crossed at the center. A diagonal lashing is used here because it starts out with a timber hitch. The timber hitch pulls the cross braces tightly together. This adds strength to the whole trestle. You have to keep a strain on the lashing rope as you complete the diagonal lashing with three wraps in each direction around the X. Then make two frapping turns between the cross braces to pull the wraps tight. Finally finish by tying another clove hitch on one cross brace.

Once the possibility of racking has been taken care of with the diagonal lashing, the trestle’s vertical legs provide support for a large downward load. Since this is a downward force, also known as a shearing force, the legs don’t have to be very big. In fact, the overall shape of the trestle is an engineered structure that is able to support quite a bit of weight with rather small-diameter spars for legs.

* An exception is building a Single Lock Bridge when the top of one trestle has to fit between the legs of the other.

Introduction to Pioneering

The following text is by Adolph E. Peschke as presented in the 1998 printing of the 1993 edition of the Pioneering Merit Badge Pamphlet:

Pioneering is the knowledge and skill of using simple materials to build structures that are used in a wide range of Scouting activities. These skills are sometimes referred to as “backwoods engineering.”

Down through the ages, people have used ropes, spars, and simple hardware to build bridges, towers, and even their own shelters. In the early development of our country, pioneering methods were used in mining and transportation, to clear the wilderness, and to build roads and bridges. So it is understandable that the term “backwoods engineering” was applied.

The same skills can be used by Scouts to build pioneering projects ranging in complexity from a simple camp gadget to a signal tower.

Whatever the project, the same applied principles of physics, geometry, and math are used to build pioneering projects and structures. But, keep in mind that all the information (in this pamphlet*) is eventually used for a practical, hands-on application—that is, to build something.

Pioneering is a good foundation for many Scouting activities. You must learn, and then use, such disciplines as planning ahead and teamwork. You can also put to use the basic skills learned in rank advancement, such as knot tying.

But most of all, pioneering provides a practical way to experience the joy of accomplishment when you’ve built something that is needed for yourself or others; it can be something that makes living in camp easier and more comfortable. Pioneering can be both fun and challenging when you use your skill and knowledge to choose the right materials (ropes and spars) and build a usable structure.

The basics of pioneering, such as tying knots, making lashings, using rope tackle, constructing anchors, and basic rope knowledge can be done at home. The projects and structures (shown in this pamphlet**) can usually be constructed with materials available at summer camp or at council camping events.

* SAFE PIONEERING

* ROPE-TOSS-LOG-LIFT CHALLENGE

* ROPE FOR PIONEERING AND CAMP USE

* KNOT-TYING TERMINOLOGY

* TIMBER HITCH

* ROUNDTURN WITH TWO HALF HITCHES

* PRUSIK

* ANCHORING PIONEERING PROJECTS

* ROPE TACKLE

* LASHING

* JAPANESE MARK II SQUARE LASHING

* MAKING A TRESTLE

* BRIDGE WALKWAYS

* PIONEERING PROJECTS

** SINGLE TRESTLE BRIDGE

** SINGLE LOCK BRIDGE

** SINGLE A-FRAME BRIDGE

** 14′ DOUBLE LADDER SIGNAL TOWER

** DOUBLE A-FRAME MONKEY BRIDGE

* PIONEERING KIT

Favorite Pioneering Knots: Timber Hitch

VIEW VIDEO: How to Tie a Timber Hitch

The following text is by Adolph E. Peschke as presented in the 1998 printing of the 1993 edition of the Pioneering Merit Badge Pamphlet in the Lashing Section describing the traditional diagonal lashing…

When putting crossed braces on a structure to keep it from racking (as used when making a trestle), the most important lashing is the diagonal lashing where the spars cross.

When the cross spars are properly assembled on the trestle, they will be standing apart where they cross. That is, there will be a few inches of space between the spars where they cross at the center of the X. To pull them tightly together, a timber hitch is used to start the lashing. As the timber hitch is pulled tight, the spars are sprung together.

and in the Basic Knots Section describing the timber hitch:

The timber hitch is a knot that can be tied quickly. As strain is put on the rope, the knot gets tighter, yet it remains easy to untie.

To tie a timber hitch, first wrap the running end around the timber log or spar. Then loop the running end around the standing part of the rope, continuing to wrap the running end around itself a few more times. This will form a hitch that will tighten on the timber as the rope is pulled. After the timber is dragged or hoisted into position, the timber hitch is easy to untie.

When pulling or lifting a timber, log, or spar, throw a hitch around it at the end that is being pulled or lifted. — Killick Hitch

A note about this final half hitch: when using the timber hitch to lift or pull an object, that added half hitch combined with the timber hitch forms what has been referred to as a Killick Hitch. John Sweet in Scout Pioneering suggests this combination when making a lobstick to throw a line over a branch. The Killick Hitch is also known as a Kelleg Hitch. The timber hitch is most always exampled as the first step in tying the combination.

Rope-Toss-Log-Lift Challenge

Link to: Favorite Scout Meeting Challenges — Racing over to the log!

If the site where you hold your meetings can feature a “permanent” crossbar about 10 feet high, then your Scouts can frequently practice and enjoy this activity whenever the opportunity is presented. Otherwise, erecting the crossbar is itself a mini-pioneering challenge, and if you have the grounds, can be regularly put up by a patrol prior to or during as many meetings as desired.

Also referred to as the Rope-Throw-Log-Lift Game and the Heaving Bar, this is an activity requiring a series of rope-handling and knot-tying skills. Because the skills that are called into play aren’t normally combined in such a sequence, and because there’s an element of fast-paced, fun competition, those Scouts knowing how to tie the featured knots most often get a kick out of giving it a go. The activity can be a competition to complete the task in the fastest time between individual Scouts or played with a team of three Scouts, each assigned a specific task.

Here’s how Adolph Peschke describes this activity in the 1993 edition of the Pioneering Merit Badge Pamphlet:

Long log! (Isn't that supposed to be a timber hitch?) — Long log! (Good Half Hitch, but is that a Timber Hitch?)

This game is intended to develop the knot tying skills of an individual Scout or of a team of three Scouts. It is important to know that the knots used (clove hitch, timber hitch, sheep shank) are each tied in a typical application for each knot. Additionally, you will develop the skills of coiling and throwing a rope.

To prepare for this challenge, you should practice tying the individual knots and coiling and throwing a rope. The challenge starts for a single Scout with the rope coiled ready to throw. The rope is thrown over the cross spar. If the throw misses the mark, the Scout recoils the rope and throws again. If the throw is good, he uses the end of the rope he is holding to tie a clove hitch on the stake next to where he’s standing.

Next he moves to the end of the rope that was thrown over the cross spar and uses it to tie a timber hitch around a short length of log (about 4 inches in diameter and 4 feet long). Then he ties a half hitch around one end of the log (forming a Killick Hitch).

To complete the challenge, he moves to the part of the rope between the stake and the upright structure, and ties a sheep shank to shorten the rope enough to suspend the log above the ground.

When the challenge is played with a team of three Scouts, the first Scout throws the rope over the cross spar and ties the clove hitch on the stake. the second Scout moves to the log and ties the timber hitch with the additional half hitch. The third Scout ties a sheep shank to shorten the rope and hold the log off the ground. The challenge comes when the game is played while being timed with a stopwatch. As a patrol, the times of the individual Scouts can be added up for a total patrol score.

The following materials will be needed so that three Scouts or three teams of Scouts can play simultaneously:

three 50-foot x 1/4 or 3/8-inch throwing ropes
two 8 to 10-foot x 2 to 3-inch legs
one 10-foot x 2 to 3-inch crossbar
two 15-foot x 1/4-inch lashing ropes
seven stakes
three 4-foot x 4-inch logs
four 20-foot guylines

To set up the upright structure, lash the cross bar to the legs with tight square lashings. About 3/4 of the way up each crossbar, attach two guylines with a roundturn with two half hitches. Stand up the structure where it will be positioned, and hammer the stakes about 12 feet out from the legs at 45° angles. So that good tension can be applied to each leg, you can attach the guylines to the stakes with a simple rope tackle.

On the throwing side, space out three stakes between the legs and hammer them in to the ground about 25 feet from the structure. On the other side space out the three logs.

SCOUT MEETING CHALLENGES MAIN PAGE

Rope-Toss-Log-Lift Challenge at the Jamboree