Key Questions to Ask When Ordering Parts of A Semi Trailer

1 Why should I buy a used trailer?
The perception behind buying a used piece of equipment is to save money, but could also be because of lack of availability. Buying a trailer from Maxim Truck & Trailer eliminates the risk of the trailer not being as advertised and the peace of mind of knowing that the equipment has been inspected by a qualified technician. 2 How new can a used trailer be?
If a trailer has been registered and the NVIS (New Vehicle Information Sheet) is destroyed the trailer becomes used. The unit could be 1 day old and be considered a used trailer. 3 Is this a good time to buy new or used?
Buying a used trailer depends on a lot of factors. One could be if the current market for new trailers is being affected by the US exchange rate, import tariffs or lack of availability. Another reason to purchase used over new is if you are venturing into a new market. To keep costs down when entering a uncertain job, buying used will help save some money in case the new work does not work out. 4 What is the availability of used trailers?
A new trailer has to be ordered and it can take two months to a year to get in. A used trailer could be sitting on the lot. Maxim is always looking for good used trailers to add to the inventory and tries to keep a wide variety of trailers available. 5 Does a trailer need to have a provincial trailer safety and does that impact the price of the trailer?
There are three ways to buy a trailer – with a new safety, the current safety, or as is. With a new safety, it’s brought in to the shop and inspected by a qualified technician who diagnoses any issues. The trailer cannot pass the provincial safety standard until those issues are repaired. The trailer will then get a provincial sticker that is good for one year from the certification date. 

With a current safety, the trailer was inspected within the past year and would have been issued a safety sticker. The sticker will indicate how long the safety is still valid for – but you will need to safety it before the expiry date and that could reveal issues you may not have realized.

With “As Is,” the safety has expired and before it can go on the highway carrying a load, it needs a new safety.

A new provincial safety can only be completed by a qualified trailer technician. At Maxim we safety our trailers to high standards to ensure the used equipment we sell is of the highest quality. 6 Why is it important to know the tire depths?
Tires are the most expensive maintenance item on a trailer. Depending on the tire, the tread depths can be quite different. A highway tire normally has a shallower depth than an off-road tire because of the application. However, despite the difference in depth, these tires can have the same amount of kilometers. While the depths are important, the side wall and tread quality also effect the longevity of the tire. 7 What is the Reefer HRS?
Some reefer unit manufacturers’ offer extended warranty on their units depending on the engine hours. HRS are the number of hours the refrigerators compressor has been running. If you have a trailer full of ice cream, you’ll want the temperature to be around -7C. Once it starts to warm up, the compressor will kick in again and cool it back down again. 8 How long can a compressor run before it needs to be replaced?
Typically, a unit runs 1,200 to 1,500 hours per year. If the trailer is on the road for five years, it should have around 7,500 hours on it.

Compressor replacement depends on how well it has been maintained. It could be after 20,000 hours if it has had poor maintenance and 50,000 for good maintenance. If a unit has less than 5,000 hours on it, you can usually still apply for extended warranty. 9 Should I ask if the reefer unit has been serviced?
Yes. It’s a good idea to get the latest reefer service report to know the working condition of the cooling unit. Buying a reefer unit is different than any other trailer. You want a service report for the box itself and the cooler unit at the front. It should be a red flag if the cooling unit has not been serviced within the last year. The oil filter on reefer engine will normally be marked with the date it was last serviced. 10 Does the reefer unit model year match that of the trailer?
For the majority, the model year of the reefer unit will match the trailers model year. However, it is a good idea to check with the local reefer dealer to find out the model year of the reefer on your trailer. 11 Does it matter whether the rear opening has swing or roll-up doors?
Yes. It’s important to get the right type of rear opening for the type of deliveries you’ve got. If you’re using loading docks, you can have swing doors because there’s room. But if you’re going down a back alley to deliver food to a 7-Eleven, there will be less room so you’ll probably need a roll-up door. It’s all about knowing your business. Having the wrong doors could make the job more difficult or impossible. You might have to bring the trailer back to get what you need. 12 Does it matter what type of floor the trailer has?
Yes. You can have a duct floor or a flat floor. Tightly-packed loads, such a drinks or meat, benefit greatly from the duct floor for the increased airflow. That kind of floor is good when you’re loading and unloading a maximum of once a day. Flat floors are more for city delivery where drivers are going in and out of the trailer more often. 13 Does how I secure the cargo on my deck impact the kind of floor I should get?
Yes. Aluminum floors have wooden strips in between for nailing down freight. If you’re weight conscious, you want aluminum floors. With wood floors, it’s cheaper to maintain or replace wood planks.

If you’re a regular hauler who is hard on equipment, you should probably get a wood floor. You can just replace the wood planks as you need them. 14 What if I’m carrying cargo that could spill?
If you have an environmentally safe trailer, you might have chemicals, which you can’t have soaking into the wood. If you have an aluminum floor, it’s easier to hose it down and maintain. 15 How thick a floor do I need?
It all depends on what you’re hauling but the thickness of the floor or type of steel in the floor can greatly extend the life of an end dump trailer.

If you’re hauling sand or gravel, that’s not too hard on the floor. But if you’re hauling cement blocks or big rocks in the mines, it can be hard on the floor. The harder the cargo you’re hauling, the thicker the floor you want and the harder the steel. On the flipside, doing so increases costs. 16 Should I get steel or aluminum wheels?
This is another balancing act. Aluminum wheels look nice and stay shiny for a long time and save weight but they’re more expensive. Steel wheels are heavier and are susceptible to corrosion but they’re significantly cheaper. Do you want the cost up front or over time? The replacement costs are $300 per aluminum wheel and $100 per steel wheel. 17 Should I buy a trailer with air ride or spring ride?
It depends on what you want and can afford. The air ride option offers a smoother ride, but it can be costly to repair or replace. It’s just what it sounds like, a bag full of air. Instead of the spring that goes up and down, the air bag goes up and down. Air rides are more expensive. For a tandem unit, it costs about $5,000 for an air ride while the spring ride is about $2,000. 18 Why does the length of the trailer matter?
You should make sure you’re purchasing the right length of trailer for the job you’re doing. A few feet can make a big difference when you’re trying to maneuver in tight places.

Trailers come in all kinds of lengths. A reefer van can be as short as 28 feet and as long as 53 feet. 19 What’s the bottom line price-wise?
Just like buying a car, buying a used trailer is a negotiation. You want to buy a trailer that helps your business be successful. It’s an asset and you will want to maximize that asset. Try to find a trailer sales rep that can be your business partner.  It is in the best interest of the dealership and the customer to be happy with the completed transaction. 20 Why is there a freight charge for used trailers?
If the trailer you’re looking for is not available in your city, there’s a good chance it can be found somewhere else. There will be a cost associated with moving the equipment to its final destination. If the advertisement says, “Selling price $20,000 FOB Calgary,” it means it’s in Calgary and you’ll pay $20,000. But if you’re in Saskatoon, it will have to be moved there. The charge to do that could be $800.

Before towing a trailer for the first time, it’s important to know the various components that make up a trailer. In this guide, we’ll walk through the basic parts of a trailer. We’ll talk about what each part is used for and why it is important.

For more information, please visit our website.

This guide is meant to be a helpful resource for those just learning to tow, as well as those who are looking to replace trailer parts on an existing unit.

Parts of a Trailer Explained

1. Coupler

The trailer coupler is the forwardmost point on a trailer tongue, serving as the primary connection point to the tow vehicle. The coupler is the trailer-side of the connection, while the hitch and ball mount make up the vehicle-side. The coupler pivots around the ball to allow for smooth driving and turning.

Most trailer couplers are made up of a cup or receiver component to accept the hitch ball, a body component that attaches to the trailer, as well as a latching mechanism to secure the coupler onto the ball.

Types of Couplers

Trailer couplers vary in style and functionality, from their body design to their latch type. Some coupler body types include straight-tongue, A-frame and channel-style, referring to the type of trailer frame the coupler attaches to.

A-Frame vs. Straight-Tongue Coupler

View Product Curt™ CURT 2" A-Frame Coupler with Posi-Lock (5,000 lbs, Black) #

SKU:

$36.95 View Product Curt™ CURT 2" Straight-Tongue Coupler with Posi-Lock (3" Channel, 5,000 lbs, Zinc) #

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$27.95

Some types of coupler latches include the posi-lock latch with its adjustable lever, the easy-lock latch with a simple push-down lever, the sleeve-lock latch for a highly secure system, as well as the pin-style or no-latch system for innovative convenience (i.e. the CURT QuickPin coupler).

Some specialized forms of trailer couplers include the lunette eye used in pintle hitch connections, and the gooseneck coupler used in gooseneck hitch truck bed connections.

4. Wiring Harness

Trailers need electrical power to operate their lights and sometimes other systems like electric trailer brakes. This power is supplied by the tow vehicle through a wiring harness.

A trailer wiring harness usually has a standardized plug that connects to a socket at the rear of the vehicle. This plug can have four wires, five, six or even seven, depending on the trailer type and number of electrical systems. There are also different configurations, such as 4-way flat versus 4-way round.

The wiring harness typically courses its way through the trailer frame where the various wires branch off to the taillight lamps, running lights, brakes as well as other electrical systems and trailer lighting.

Types of Trailer Wiring

Even though trailer wiring has become quite standardized, it can be confusing when you start to discover how many different varieties there are. 4-pin flat, 6-wire square, 7-way RV blade – what does it all mean?

First, the number in each configuration corresponds to the number of wires that make up the connection: 4-way has four wires, 5-way has five wires, and so on. These wires are color-coded and are used for specific functions, based on the color: green is for the right turn signal / brake light. Brown is for the taillights. White is the ground connection, etc.

All Trailer Wiring Types Color-Coded by Function

Secondly, terms like way, pin, wire and prong are all synonyms. Simply put, they all mean the same thing. You can call it a 4-way, or you can call it a 4-wire, or you can call it a 4-pin – it’s the same configuration.

Link to longyong

One caveat is that blade is more of a reference to the style of the individual contacts. Instead of a pin, each contact point is a flat blade-like piece of metal. On RV blade harnesses, the blades are arranged in a circle, which brings us to the final point.

Lastly, the terms flat, round and square are indicative of how the wires are arranged. In a flat configuration, the wire contacts are all laid out in a single, flat line. In round, the wires are in a circle. You get the idea.

Some Different Wiring Examples

View Product Curt™ CURT 4-Way Flat Connector Plug with 48" Wires (Trailer Side) #

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$8.95 View Product Curt™ CURT 4-Way Round Connector Plug (Trailer Side, Packaged) #

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$8.95 View Product Curt™ CURT 6-Way Round Connector Plug (Trailer Side, Chrome Plastic) #

SKU:

$8.95 View Product Curt™ CURT Heavy-Duty 7-Way RV Blade Connector Plug (Trailer Side) #

SKU:

$9.95

When considering wire harness types and perhaps which one to buy as a replacement, the best course of action is to look at what you already have on your trailer. If it’s a 4-way flat, replace it with another 4-way flat. If it’s a 7-way RV blade, replace it with a 7-way RV blade.

5. Safety Chains

Safety chains are a backup connection between the tow vehicle and trailer. If ever the primary hitch connection should fail, the chains are designed to maintain the connection until the vehicle can come to a safe stop.

Trailer safety chains are relatively short in length – usually around four feet – and come in a variety of material and weight capacity options to accommodate different trailer types.

Two safety chains (or safety cables) should always be used on a standard trailer hitch setup. The correct way to connect safety chains from the trailer to the vehicle is to cross them once underneath the coupler. 

A Note about Proper Safety Chain Hookup

It is typically recommended that you only cross your safety chains one time under the coupler. This allows proper chain movement while turning and creates a cradle for the coupler in the event of a disconnect.

If you twist the chains around multiple times, it could create a situation that the chains may bind while turning. In the event that your chains are too long, there's another trailer accessory that we recommended that you use: a safety chain hanger. Safety chain hangers attach easily to your trailer hitch to keep your chains from scraping on the ground.

13. Fenders

The fenders of a trailer serve as shields around the trailer wheels, helping to contain dirt, debris, water and other road elements from getting kicked up by the tires. Just like on a vehicle, the trailer fenders block this debris, deflecting it back toward the road and keeping it away from your cargo, the body of the trailer and other vehicles.

Trailer fenders are oftentimes constructed from metal and can take many different shapes, whether they hug the wheels in a clean curve or are angled for a squared off look. Some fenders are integrated with the body of the trailer, and others are flared, sticking out like the style of a flare-side pickup truck bed. There are also single-wheel fenders, tandem fenders, triple-wheel fenders and so on.

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