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  1. Trailer Door Hinges
  2. Redline
  3. Hinge Pin
  4. Build Your Own Hinge
  5. 4-1/2 Inch Long
  6. 1/2 Inch Diameter
1/2" Diameter Hinge Pin, 4-1/2" Long

1/2" Diameter Hinge Pin, 4-1/2" Long

Item # HP412
Our Price: $5.98
Trailer Door Hinges
Shipping Weight: 0.27 lbs
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Hinge pins are welded to either the outer frame or the gate/door and then inserted into the welded hinge pin nipples to create custom, heavy-duty hinges. Great Prices for the best trailer door hinges from Redline. 1/2" Diameter Hinge Pin, 4-1/2" Long part number HP412 can be ordered online at or call 1-800-940-8924 for expert service.
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  • Reviews (5)
  • Q & A (0)
  • Photos

Redline Trailer Door Hinges - HP412

  • Hinge Pin
  • Build Your Own Hinge
  • 4-1/2 Inch Long
  • 1/2 Inch Diameter
  • Redline

Hinge pins are welded to either the outer frame or the gate/door and then inserted into the welded hinge pin nipples to create custom, heavy-duty hinges.


  • Build your own hinge
  • Great for trailers and agricultural applications


  • Outer diameter 1/2"
  • 4-1/2" long

HP412, Hinge Pin 1/2" OD 4 1/2" Long

Customer Reviews

1/2" Diameter Hinge Pin, 4-1/2" Long - HP412

Average Customer Rating:  4.8 out of 5 stars   (5 Customer Reviews)

Hinge pins are welded to either the outer frame or the gate/door and then inserted into the welded hinge pin nipples to create custom, heavy-duty hinges.


Got what I wanted and I’m satisfied. Th anks!


Exactly as described and what I was looking for! Had previously ordered from another website and got the tiny spring part, not the actual hinge pin. Apparently some businesses listing on [online] don't know the difference in parts-part names, and the other site's photos were enlarged so it coukd have beenthe 4 1/2 inch pin. Here, this is exactly what is needed. Its a good solid part and workmanship with no sharp edges from sloppy cuts either. Fast delivery. Searched many supply places online and in person before finding and bookmarking this site forfuture use!!


Perfect replacement for missing pin on 2000 car hauler.


Well you guys did a great job but I ordered the wrong size! Lol



See what our Experts say about this Redline Trailer Door Hinges

  • How Much Does the 1/2" Diameter Hinge Pin, 4-1/2" Long Weigh
    The 1/2" Diameter Hinge Pin, 4-1/2" Long part # HP412 weighs around 4 ounces.
    view full answer...
  • Replacement Hinge Pin 6-1/2 Inches by 1/2 Inch
    We don't have a 6-1/2 inch length but we do have the 1/2" Diameter Hinge Pin, 6-3/4" Long # HP634 which can be cut or ground down to the 6-1/2 inch length.
    view full answer...
  • Can All Left or Right Heavy Duty Trailer Ramp Springs be Used to Replace 2 Ramps with 1 Long Ramp
    Since you are removing the 2 ramps and putting in a single ramp then you can use all left or all right ramp springs as long as they engage the ramp like they are supposed to and there is room to mount them. Regarding your follow-up question, yes, that is correct. The spring tension will occur when the ramp opens. That tension will help support the weight when lowering and when lifting the ramp. It sounds like you have a good handle on this already!
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  • Will the Redline 1/2 Inch Hinge Pin Nipple Work with the 1/2 Inch Diameter Hinge Pin
    The 1/2 Inch Diameter Hinge Pin Nipple # HPN214 referenced in your question will work perfectly with the 1/2 Inch Diameter Hinge Pin # HP412. I actually went out to our warehouse to test the two items together and the fit is not too tight at all. We have measured the inner diameter of the hinge pin nipple with a digital caliper in the past and found a true diameter of right at 0.52 inches, making it compatible with a 1/2 inch hinge pin.
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  • Removing Rusted Hinge Pin on Trailer
    You can try heating the nipple with a torch and then using a punch to drive out the pin. Be gentle with the heat, as the idea is to get the nipple to expand without heating the pin to the extent that it expands as well. When driving the pin out, be careful not to mushroom the end of the pin. For multiple hinges, you might have to remove the pins a little at a time. If that does not work, you will have to use an angle grinder to remove the nipple and pin completely, then start over with...
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  • Rear Door on Circle J Horse Trailer Has Play in It when Closed
    From what I could find the Circle J horse trailers use a sort of cam-lock design similar to what you might see on a big rig trailer # 383200 or a side door bar lock like # 305736. These designs work fine until something gets knocked out of alignment. The most likely cause is damage to the door or a hinge problem. If the door is warped or if you are able to wiggle the door at the hinges then that would be the issue. Straightening out the door or repairing it as needed and repairing the...
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  • Can Barn Doors of Trailer Ramp be Changed to Ramp Door
    Most likely it's possible but the level of modification you'll need to do is hard to say. We have ramp door hinge kits like the part # PLR1904-Z which you'd weld to the back of the trailer and then attach a ramp door to. But most likely you won't be able to reuse the barn doors and you'll have to come up with a ramp.
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  • Can the Ramp Spring # RS16933LH Be Installed on a 1-1/4 inch Diameter Pin
    The inner diameter of the Ramp Spring # RS16933LH that you referenced is 1-1/2 inches, you could easily use this spring on a hinge shaft that is 1-1/4 inches in diameter. I spoke with my contact at Redline to confirm this.
    view full answer...
  • Replacement Ramp Springs for Horse Trailer
    Horse trailers are enclosed, but they usually don't use the enclosed trailer ramp springs for the safety of the horses. They use smaller versions of our heavy-duty ramp springs. Unfortunately, we only carry the heavy-duty versions at this time, meant for heavy-duty steel ramps like those on equipment trailers or car haulers.
    view full answer...
  • Trailer Ramp Spring Assist Recommendation for a 44 inch Wide Trailer Ramp
    The best ramp assist spring recommendation I can make for you would be the Enclosed Trailer Ramp Spring # 362SA7. Check out the review video I attached to the right. The installation instructions for this product are recommended for individuals who have experience winding torsion springs. If you have not worked with a torsion spring system before, we recommend contacting a local garage door company to install this system.
    view full answer...
  • Troubleshooting Ramp Door Spring Not Opening Properly After Snapping Cable with Reinstall
    Sounds like the torsion spring of your ramp door assist hasn't been wound properly and that's why the door isn't opening properly. This can be a dangerous endeavor so recommend you find someone with experience winding torsion springs and have them get everything set back up at the proper tension. Local garage door companies would be who to check with.
    view full answer...
  • Hitch Recommendation for a 2015 Chevy Traverse
    For a hitch for your 2015 Chevy Traverse you would want the Draw Tite Hitch part # 75528. See the install video I attached. For wiring you would want the part # C56181. For ball mounts I recommend the etrailer Ball Mount Kit # 989900. It comes with 2 ball mounts, 2 balls, a hitch pin with clip, and a carrying bag.
    view full answer...
  • Trunk Mounted Bike Rack Recommendation for a 2016 Mazda 3
    The Thule OutWay Bike Rack part # TH45JV has been confirmed as a fit for both the hatchback and sedan models of the 2016 Mazda 3 so I would recommend it for you. What makes this rack far superior to the others is the attachment system. It uses only 2 retractable coated steel cables to attach to the vehicle rather than 6 nylon straps like other racks. This makes installation quick and easy and the cables also last longer. The cables store inside the rack so there are no loose straps ends...
    view full answer...
  • Trailer Ramp Springs for a 20 Ton Tandem Axle Trailer
    That sounds like a very heavy duty trailer. For heavy duty trailers there are special ramp springs, # RS16933RH for right hand side and # RS16933LH for left hand side. They fit a 1-1/2 inch diameter shaft or hinge pin. We do not have a pin that large. I have included a link to a video review of the springs for you. The other springs we carry are all lighter duty for enclosed consumer trailers and probably would not be strong enough to fit your 20 ton trailer.
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  • Ramp Spring Recommendation for a 20 ft x 7 ft Equipment Hauler with Adjustable Width Ramps
    Yes, the Ramp Spring - 2K Torque for 1-1/2" Shaft - RH # RS16933RH would work on the right side of your trailer and the Ramp Spring - 2K Torque for 1-1/2" Shaft - LH # RS16933LH would work for the left hand side of your trailer. Both of these springs are designed for use on 1-1/2 inch diameter shafts so they would fit very well. I attached a picture we got from a customer who used these springs on an adjustable width ramp just like you plan on doing.
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    Image 1 for
  • How Do the Heavy Duty Ramp Springs Install on a Trailer and Ramp
    Heavy duty ramp springs # RS16933RH and # RS16933LH install on the hinge of the ramp. I have included a picture of what this looks like for you. Not all trailers are exactly the same but this should give you a general idea of how the springs install.
    view full answer...
    Image 1 for
  • Ramp Spring Weight Capacity and Left or Right Hand Orientation for a Horse Trailer
    The right hand ramp spring, item # RS16933RH, and the left hand spring, item # RS16933LH, are differentiated by paint on the springs from the manufacturer. The springs with green paint on them are right side springs, left side springs are unpainted. Right side springs will go on the right side of a ramp and left hand springs go on the left side of a ramp. Both right and left hand springs deflect in the same direction the designation of right and left has to do with orientation of the stick...
    view full answer...
    Image 1 for
  • Replacement Trailer Ramp Springs
    We have several hinge pins like # HP412G that I have linked for you, but it sounds like you need actual springs. We have some heavy duty ramp springs like # RS16933RH and # RS16933LH if you happen to have a heavy duty equipment trailer like what they haul tractors and other large equipment on. For an open utility trailer you may be able to use a tailgate assist like # RA-27C. Or for an enclosed trailer we have springs that are similar to garage door systems. I have linked those as well....
    view full answer...
  • Rear Ramp Door on Pace Enclosed Trailer Does Not Open or Close All the Way with Hinge Springs
    It sounds like there could be something bent either on the ramp itself, the body of the trailer or the spring or hinge pin. You could replace the hinge type springs with an enclosed ramp spring system such as # ERS120D81 at 81 inches wide and 120 pound capacity but if something is bent then it will still have the same issues. If you have at least 80 inches, you may want to consider replacing with # CB250D96SHD which is rated for 250 lbs. The installation instructions for these products...
    view full answer...

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Info for this part was:

Employee Lindsey S
Written by:
Lindsey S
Employee Leah B
Edited By:
Leah B

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