window springs

Constant Force Window Balance Springs

As the world leader in constant force spring technology,
John Evans’ Sons (Est. 1850) has produced well over 100 million
high performance balance products.

The following innovations are the result of John Evans’ Sons unparalleled
experience and technical expertise.

di SERIES

        …the most technologically advanced Drop-In balance system for hung windows.

              drop-in series constant force balance system logo & graphic

        Offers the following:

              • low cost and a reduction of on-hand inventory
              • quiet operation with low operating forces
              • superior cam strength & reliability
              • higher weight AAMA qualified springs
              • Patents: #8,458,878 / #8,640,383 / #9,334,683 / #9,371,677 other patents pending

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Drop-In Balance System

Drop-In Balance System Intro.
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1/2" Drop-In Series

1/2" width Drop-In Fabrication Instr.
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3/4" Drop-In Series

3/4" width Drop-In Fabrication Instr.
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Drop-In Balance System

Drop-In Series Spring Load Chart
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Drop-In (Di-500) 1/2" width Demo

Four Step Installation Instructions

SideLoad™ Constant Force Balance System

          …a better option for side load windows.

                SideLoad logo & graphic

          Our SideLoad™ Constant Force Balance System uses AAMA qualified springs and is a simple conversion from block & tackle.

          Compared to block & tackle, the SideLoad™ Constant Force Balance System offers:

                • a lower price
                • significantly reduced operating forces
                • a substantial reduction of on-hand inventory
                • dramatically smaller space requirements
                • a tighter fitting sash
                • Covered by one or more of the following patents & patents pending: US PAT#7,980,028 / US PAT#8,181,396 / US PAT#8,424,245 / US PAT#8,505,242 / CAN PAT#2,707,434 / CAN PAT#2,707,562 other patents pending

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SideLoad Balance System

SideLoad Balance Intro.
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SideLoad Balance System

SideLoad Installation Instructions
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SideLoad Balance System

Slot Milling Instructions
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SideLoad System Sash Cam

Sash Cam Dimensions & Mounting
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SideLoad Balance System

SideLoad Spring Selection Chart
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SideLoad Balance System

One Piece Sash Guide Instructions
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SideLoad Balance for WOOD

SideLoad for WOOD Intro.
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SideLoad Balance for WOOD

SideLoad Installation Instructions

the SideLoad™ Balance System Demo

        the NEW SideLoad™ Sash Cam Demo

the SideLoad™ Balance Sash Guides & Sash Cam Component Review

Constant Force Balance Springs

          Today’s window requirements demand quality and consistency. Springs need to pull their weight…and no less.

                Constant force spring characters lifting weights

          Our AAMA qualified springs do just that, no matter how high the rated load.

                • ½” Series: 3 lb. through 10 lb.
                • ¾” Series: 3 lb. through 13 lb.
                • ⅜” Egress Series: 4 lb. through 7 lb.

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Constant Force Balance Spring

1/2" Spring Selection Guide
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Constant Force Balance Spring

3/4" Spring Selection Guide

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Got A Question? Consult our Experts.

Our experts offer a depth of expertise to assist you with all parts of the process. We are ready to answer your questions in a timely manner and will help you define what you need. We produce custom springs for all purposes, and we are here to work with you on any of your customization needs.

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