Project Description
Johns Hopkins University Applied Physics Laboratory | Laurel, Maryland
Project Description
Founded in 1942, the Johns Hopkins University Applied Physics Laboratory (APL) is a not-for-profit university-affiliated research center in Laurel, Maryland, known for advanced engineering and rapid prototyping. The lab’s mechanical design team needed a hinge solution for a circular hatch door assembly weighing about 100 lbs that had to close softly without slamming. Mounting space around the round hatch was limited, so the hinges had to fit a compact plate while keeping the heavy door stable and controlled.
Waterson recommended a pair of K51P hydraulic hybrid hinges mounted symmetrically above and below the hatch center, because a single hinge could not provide enough closing control to prevent slamming. The built-in hydraulic mechanism regulates closing speed through the swing, while the two-hinge layout shares the load and keeps the hatch aligned. The team ordered both a standard version and a hold open version, giving them flexibility during prototyping and allowing the hatch to stay open for access or maintenance.
Waterson Product
- K51P-500-B2-US32D: Full surface 5 inches x 5 inches, soft closing, satin brush finish US32D, heavy-weight duty, adjustable closing speed, 304 stainless steel.
- K51P-500-D2-US32D: Full surface 5 inches x 5 inches, hold open, soft closing, satin brush finish US32D, heavy-weight duty, adjustable closing speed, 304 stainless steel.
Fill out the form below and request a trade discount for your project.
Media:
Request For Quote
Please note that Waterson Closer Hinges start from a size of 4″x4″. If you’re in need of smaller self-closing hinges, we’d recommend checking out some other resources! Also, we only provide single acting closer hinges. Thank you.
Recent Post
Replacing Door Hinges: 1/4 vs 5/8 Radius vs Square Corners
Quick Answer Most 4 inch residential door hinges have one of three corners: square, 1/4" radius, or 5/8" radius. A rounder hinge fits a mortise [...]
Why Won’t My Self Closing Door Hinges Close in Cold Weather
Quick Answer An exterior door that closes fine in summer but won't latch in winter is usually affected by two things: weather stripping that stiffens [...]
Soft Closing Hinges: 9 Most Frequently Asked Questions
Since the AIA in 2018, there has been an increased interest in Waterson hinges for many different projects. We have been inundated with questions by [...]





